Ah, that was unclear from your formulation. However, to go along with that, the rogue cannot perform that way at 11th, which is tier 3. Then, suddenly, at 12th, they can.
Actually, Reliable Talent is the Rogue’s 11th level feature. 11th level is the start of 3rd tier, and every class gets a significant boost at 11th level. Full spellcasting classes can’t cast 6th level and above spells at 10th, and suddenly, at 11th, they can. Fighters can only attack twice per turn at 10th, and then, suddenly, at 11th, they can.
Again, you have a high failure rate in your game, statistically. Assuming a 50/50 shot is reliably passed is madness. You've set up your baseline for 'easy' as requiring additional resources to accomplish. Nothing wrong with having your games set at a higher difficulty setting, but you shouldn't fool yourself into believing that it's not.
I never said a 50/50 chance of success was easy. I said I expect players to be able to pass it. If I didn’t expect that, i’d find my players succeeding unexpectedly half the time, which is absurd. Note that expecting players to reliably be able to succeed at something is not the same as expecting them to be unable to fail at it. If that was my expectation, I wouldn’t even ask for a roll.
Quote me saying this, please.
You said it’s a bad feature. If you don’t think most DMs find it to cause problems, then by what metric do you evaluate it as a bad feature?
Um, no, because, by definition, half of those checks fail. What you're confusing for the difficulty of the class is how your players have adopted to your strange idea of probably by throwing more resources to increase their odds at success because you've set the bar for normal too high.
50% chance of success is not “my bar for normal”. The way DCs are designed to work in 5e, with its bounded accuracy, is that DCs are consistent regardless of PC skill. So a normal (or rather, medium) task is always DC15. I expect that, by 3rd tier, normal tasks no longer present a meaningful obstacle to PCs. Hard tasks may or may not, depending on the skills at each PC’s disposal, but I certainly don’t expect them to present a meaningful obstacle to the classes whose niche in the party is to be the best at skill checks. If it’s said character’s area of expertise, I don’t expect to be able to challenge them with anything less than a Very Hard task. This is appropriate given the tier of play and the Rogue’s role in the game. Given this baseline expectation, Reliable Talent doesn’t bump up the difficulty of tasks I can expect to challenge the rogue with, it only removes the chance of failure on tasks I already didn’t expect them to be challenged by.
And, with that said, do you not notice that difference between 'I need to use guidance and some bardic inspiration to make this 50/50 shot likely to succeed" and "i have reliable skill now so I don't need to use guidance and bardic inspiration on that check"?
Of course I recognize the difference. That difference is pretty much the point of the class freature in question. It saves the party from having to expend as many resources. That’s pretty much what all character progression in D&D boils down to - being able to take on more difficult challenges without expending as many resources.
Because it's a bad design feature -- it's sudden and radically redefines what challenges the rogue. This would be acceptable if all classes had such a break near the same level, but none of the other classes do. None of the other classes entirely remove a common obstacle via a class ability in this manner -- if I could challenge a fighter at 11th with a creature, then at 12th that creature is still a challenge, even if less of one. Reliable Talent pretty much removes a huge swath of previously effective challenges.
But there are plenty of creatures that challenged the fighter at 10th that no longer do at 11th, because his damage output just suddenly increased by about 33%. I would also argue that the “challenges” Reliable Talent removes aren’t really challenges. Even if you aren’t willing to grant that DC ~20 tasks don’t challenge 10th level rogues, they certainly aren’t challenged by anything DC ~15 or below, and the roll, if you even call for one, is largely a formality at that point. The feature is more about security against the odd crap roll on an otherwise unchallenging task than about allowing you to take on more challenging tasks.
And, even if you persist in your assumption that 50/50 is probably successful due to other resource expenditure (or retries), then it should still be apparent to you that the ability removes the need for the additional resources or retries, which alters how those challenges work in your game.
To clarify, I don’t allow retries. If there is nothing preventing the players from retrying, I just skip the roll and say that they are eventually successful. And that’s why this doesn’t seem like a problem to me, because the situations where an 11th+ level rogue is faced with a DC ~20 task and actually needs to bother rolling are already few and far between in my games.
Having a solution to this issue in my game doesn't remove the issue from the game, nor does it obviate the usefulness of clearly identifying the issue and discussing it so that others can evaluate it for themselves and adopt (or not) a solution for themselves. Again, the idea that a problem might be locally removed for you doesn't mean it's not worth discussing, if only to get a better grasp on how others play the game. You're limiting your ability to learn if you try to shut down discussion.
I’m not trying to shut down discussion. “This feature causes problems in my games, can folks advise me on how to deal with it?” is a valuable discussion to have. “This feature might cause problems for some DMs and here are some suggestions on how to deal with it if you need to” is a valuable discussion to have. “This feature is badly designed” is a raw complaint, and that is what I object to.