Playing a Strong Club (or Strong Diamond) system means that natural opening bids can be limited to a maximum of 15 HCP or so. Since these opening bids do show shape, their maximum strength is useful information. (Even the nebulous 1D opening found in some versions of Precision at least carries the negative inference that opener does not have (or is very unlikely to have) a 5-card major, and this is a useful type of shape information since it limits how good a major-suit fit the partnership can have.) Indeed, it is often said that having limited opening bids is the real purpose behind playing a Strong Club system.
However, I would not say that it is such a great advantage. For simplicity, let's consider just the major-suit openings. The hands which are removed from 1M by the Strong 1C opening are strong and mostly unbalanced, and so these hands are usually worth a second bid in competition (though they may not be completely pure two-bid hands). So whether these hands are opened 1M or not does not really affect the homogeneity of the 1M opening bid. Responder will initially be trying to cater for opener's minimum hands, and so excluding hands of 16+ HCP from the opening bid rarely makes a difference to responder's bidding on the first round. On later rounds, opener will have had the chance to show his strength more precisely.
Of course, knowing that opener is limited is not completely useless to responder. In particular, when responder has a minimum game-forcing hand, the limited opening may be sufficient to rule out the possibility of a slam. This means that responder can take a direct route to a game contract, rather than having to leave room in case opener had a very strong hand and wanted to make a slam try. The most well-known example of this is responder's direct raise to 4 of opener's major. In natural systems this bid would only be made on a weakish but distributional hand, based on excellent trump support. But in Precision it is also possible to raise directly to game with stronger hands: those which are worth game based on high-card strength, maybe 13 HCP or so with 3-card support. By reaching your best contract in two bids you avoid giving information away to the opponents, and if an opponent has a hand which might be worth competing over the game bid, it will be more difficult for him to judge correctly now that the jump does not promise a big fit. However, responder is aiming at quite a small target here. Even opposite a very limited opening, there are not very many hands that can be certain of wanting to play in game but also fairly confident that there is no slam available. Opener may be limited in high-card strength, but he is not limited in distribution, and there are very often some well-fitting distributional hands which would make slam good. And also, if the opponents do compete, it is now opener who is disadvantaged by not knowing responder's hand.
In any case, the immediate raise to 4 is rather a special auction. There are not many other situations where the limited opening bid is immediately useful to responder. For example, if opener's LHO overcalls 3C, then responder will have to bid 3NT (say) on almost exactly the same hands as he would if the opening bid was unlimited. Of course, when holding a good hand for the bid, responder will be happier opposite a limited opening because this reduces the chance that a slam will be missed. But the point is that when opener has a weaker hand the bidding will be the same after a limited opening as it would have been after an unlimited one. When this is the case, in order to compare different systems we only need to look at the stronger hands, and ask whether they are better opened with a natural unlimited opening or an artificial strong opening.
You see the real advantage of limited openings when opener gets to make his rebid. Playing unlimited suit openings, opener's rebids have to cover all the strong hands. With limited openings these strong hands are ruled out, and so opener's rebids do not cover such a large range and can be more descriptive. But note that it's not actually necessary to remove all the strong hands in order to do this. If the natural opening contains a restricted number of strong hand types, this still makes the rebids more descriptive than a standard unlimited opening: it doesn't matter that the bid would still be wide-ranging in terms of pure high-card strength. It might make sense, therefore, to use a strong (or multi-way) opening only for hands which are particularly easy to describe by starting with a strength-showing bid (such as strong major single-suiters), and use natural openings for other strong hands.
All in all, it is not the immediate definition of maximum strength which is the advantage of limited openings. Rather, limited openings are a way of re-arranging the meanings of opener's rebids, in the hope that hands will be better defined after the second call (and with easier continuations) than if you were using unlimited openings. But of course there are very many other ways you might try to do this, and it should be better to analyse the various hand types more closely, trying to find the best way to show shape on unbalanced hands and strength on balanced hands.
Pairs who play limited openings often open lighter than is standard. That is, while they have removed a large number of strong hands from the natural bids, this is compensated by opening more hands at the minimum end of the range. However, while there is a lot to be said for opening light, I feel that the argument that light openings go naturally with a limited opening system is largely fallacious. As was said earlier, removing the strong hands from a bid does not really affect its homogeneity, since the hands removed are mostly two-bid hands. But opening light does affect the homogeneity of the bid - the hands that are added are definitely one-bid hands. So it doesn't matter whether you decide to play limited openings or not, opening light makes your bids less homogeneous. Again, limited openings may help with the rebids, but not with the initial description of the hand. So by all means play light opening bids, but you don't need a limited opening system to do so. You would only see an effect if you were prepared to play a strength-showing opening which took out significant numbers of one-bid hands, and that would mean it would have to start at about 14 HCP - maybe even less. This might be necessary if your opening bids start really light (an 8 - 13 HCP opening bid is playable whereas 8 - 17 HCP is probably not), but including lots of unbalanced one-bid hands in a strength-showing opening is not such a good idea, as we have already seen.