Tony Vargas
Legend
I haven't noticed that - not in 4e, when Combat Advantage was a single, invariant (+2), non-stacking bonus, not in 5e with Advantage (not that either were entirely non-stacking, if you get a bonus from Bless, for instance, it 'stacks') - but then I haven't exactly been looking for it. IMX, players who are inclined to come up with interesting narrations do so regardless of system benefits or lack thereof. Those who are inclined to chase bonuses might try to come up with an 'interesting narration' if it'll earn them some additional bonus, of course, but often they just come up with an annoying narration (JMHO, but it's also why I'm not wildly enthusiastic about indy 'rewarding RP' mechanics).I think it goes beyond simplifying combat: I believe a single, invariant, non-stacking bonus encourages players to focus on the most interesting narrations they can come up with, rather than the ones that will confer the best statistical advantage.
Actually - and this just strengthens your point, in a way - Advantage isn't exactly invariant, the benefit it gives is on a sort of sliding scale, the closer your chances of success are to 50/50 the greater the impact, so if you do have some other bonuses, the advantage of Advantage is less advantageous. So if you are starting near 50/50 it minimizes the benefits of bonus-hunting (OTOH, if your chances are bad to start, scraping together some bonuses makes Advantage that much better). That's one thing I do like about Adv/Dis is that the extremes are self-limiting.
By the same token, once you find a consistent way of getting advantage, you can do things in that rote, cookie-cutter, advantage-getting way, rather than exploring further narrative space that might have gotten you more or stacking bonuses in some hypothetical system.Once you've got Advantage you can't improve your odds any more, so there's no incentive to do things in a rote, cookie-cutter way that stacks the best bonuses. It frees up your narrative space.
That, I have seen (both with 4e CA & 5e Adv/Dis), though even then it's not as chilling as all that. Players will still end up getting CA on someone already granting CA or having Advantage three different ways, perhaps because it's bundled with something else, or there's just no reason not to, or one player's set-up overlapped with another's condition-infliction or buff.