That's not necessarily true. The concept of bounded accuracy doesn't inherently include a specific value of accuracy that is the maximum boundary, nor does it inherently include a mandate that all forms of accuracy (attack vs. AC, saving throw vs. DC, and ability check vs. DC) be set to the same maximum boundary.
So the "double proficiency" features only actually break bounded accuracy if the designer didn't intend the level of accuracy that they give to be possible for the type of accuracy they give. And since there are no "double proficiency" features that add to attack rolls, saving throws, or save DCs, I think it might well be deliberate that ability checks can reach the level of accuracy that you view a "break."
You mean that expertise, which specifically apply to skill checks, doesn't have anything to do with the bounded accuracy assumptions for AC or saving throws? Wow, had not realized that.
Every one of the things I referenced only deal with skills, which, coincidentally, are the only things that have static, objectively set DC thresholds. So, yeah, I'm quite aware that the issues I'm discussion don't have anything to do with ACs or Spell DCs. And, regardless of whether or not designers intended it, the break in concept between a objective DC and the ability to easily surpass what is supposed to be very hard or impossible is a problem. I do not think that the effects of expertise were well tested in the mid to high tiers of play alongside the DC thresholds. A 13th level rogue with a single uncommon magic item can pick every lock in the game without having to roll (assuming a fixed upper bound of DC 30, which I don't agree with but have been vigorously challenged for even contemplating otherwise). Without the magic item, he picks all DC 25 or less locks without a roll. It's hard to justify the sudden appearance of massively complex (and expensive) locks everywhere I want to slow a party, so my choice is generally to stop putting in locks for the rogue to pick or ignore that there are locks with a mere narrative gloss. At level 20, I'd have no problem with that, but 13?
And then you get into contested rolls. Expertise in stealth murders the vast majority of passive perceptions. This is even without reliable talent. A 9th level character with an 18 DEX has a Stealth of +12 with expertise. This beats a passive of 12 without a roll. Add a 20 DEX and a luckstone and it's auto success against 14 passive perceptions. That's a large chunk of the monster manual, without a roll.
Expertise on athletics paired with grappling is also broken (given the most things are even proficient in athletics).
Almost all of these issues become much more tolerable if you nix expertise and other double proficiency bonuses. Just swapping it for advantage makes things work much better because it doesn't mean you suddenly get to do things you couldn't before or that really hard things become easier, but that things that you should be good at doing you do far more consistently. Which is what expertise to represent.
That all comes down to preference.
You mean that, in a thread asking for preferences and dislikes, my answer is my preference? Wonders, will they ever cease?