We don't talk about Pun-Pun
Excuse me, I'm not using an interpretation of the rules to be restrictive, lol. I'm telling you what I've endured personally, as to why I feel Stealth is a sucker's game.Stealth isn't shut down by enforcement of the rules.
You are using an interpretation of the rules to be the most restrictive.
5e rules are actually pretty lenient by using passive perception and having the entire party be able to do it via group checks, even if there is a heavy armour user. 1 can fail and the group can still pass as the stealthy characters help them.
Or not even using a group check a rogue can use their action to help another character while using their bonus action to hide. That gives advantage or cancels out disadvantage.
But more to the point:
Group ChecksTo make a group ability check, everyone in the group makes the ability check. If at least half the group succeeds, the whole group succeeds. Otherwise, the group fails. Group checks don't come up very often, and they're most useful when all the characters succeed or fail as a group.
So if our group has a heavy armored Fighter (untrained, Dex, say, I don't know, 12?), a medium-to-heavy armored Cleric (untrained, Dex ranging from 10-14), a Wizard (untrained, Dex 14-16), and a Rogue (trained, maybe expertise, Dex 16 or better), hang on, let me math...
Ok average roll with disadvantage is 7.18, average roll is 10.5....so we'll say our hypothetical results are...
Fighter 8, Cleric (halfplate 14 Dex*) 9, Wizard 13, Rogue 17....the group fails if the passive perception of foes is 13. Which I'll grant, is better odds than I've seen in play. So on paper at least, you're correct that my argument here is based on anecdotal knowledge, not real data. And maybe I gave up on Stealth in 5e too soon, given my horrible experiences with it in previous editions.
*The Breastplate exists, but I've never seen anyone use it at a table; they either have much cheaper medium armor and are fine with that, or if they upgrade, they want the best AC. YMMV!
OTOH, group composition matters. A character can't expect Stealth to work just because they're good at it, which still puts it somewhat at odds with other kinds of ability checks (above and beyond the already swingy nature of ability checks in 5e). They either need to put themselves at a distance from their party (which could lead to a solo encounter if they are unlucky) or, if possible, ask some important questions during Session Zero about the playstyle and builds of their fellows.