Here is a quick table of the most common classes using the most common race.
There are only so many proficiencies a character can select or select from. There are only so many ASI's or ability scores bonuses at all. There are a lot more checks than any character can be proficient and there are many checks for which proficiency does not exist at all.
The big numbers being discussed are outliers. The only way to get them is to stack on bonuses to make bigger numbers for the sake of making bigger numbers. In my table I used stealth and perception expertise because they keep coming up per this thread, and felt the need to give them to the fighter because...
Players Hand Book page 175 said:
When a number of individuals are trying to accomplish something as a group, the DM might ask for a group ability check. In such a situation, the characters who are skilled at a particular task help cover those who aren't. To 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.
...so when a group is moving stealthily anywhere the choices are everyone makes a roll and the group very rarely surprises or the group makes a group check and needs half the group to make the check to succeed. Sneaking up on anyone is restricted by the poor checks, not the good check by the rogue unless the team splits up.
Adding in a spell like pass without trace is not typical because it requires having a class in the party who could have it and having that PC take it and having that PC expend a limited resource on it's use including considering opportunity costs.
If a PC makes that investment and gives up the opportunity to use that spell slot elsewhere to hide from enemies that's what the bonus is for. It's to help the characters who suck at stealth (like that cleric with no skill or natural ability and disadvantage on the check from his armor) just so the group can succeed. Not a bad thing. The super high bonus it also gives the rogue is superfluous.
The other thing to remember is stealth is a conditional ability. A character cannot hide without cover or concealment. The chance to walk across a clear open field in broad daylight with guards are posted in the watch towers and at the gates is zero regardless of how high the bonus is.
So if a group casts pass without trace and invisibility in a high enough level slot to cover the party and makes a group check to drastically increase the odds of success (because low DEX heavy armor can still easily blow it without the group check) then that's not really easily all the time kind of tactics. And the low DEX heavy armor no proficiency characters can still blow it even with all that. It's not like that wizard / warlock / sorcerer is pro at stealth checks either.
Perception is also something that's limited. A character who is distracted by other activities (unless a ranger in his terrain) do not get to make perception checks in the activities stated in the PHB, or others at the option of the DM.
A high bonus that is denied isn't going to do anything, although this is typical of wilderness travel tbf. Groups who set a watch are limited by the perception of the PC who is on watch at the time. The general benefit of high perception most of the time is simply not getting surprised. That's hardly game breaking.
Official WotC adventures practically never go above DC 20 for anything.
It sends the message "everything is pathetically easy" for the focused character.
Again, any sensible home DM would apply common sense. I see you have done precisely that. I just wish official guidelines were based in the same reality as characters created from the Player's Handbook...
Or it might be sending the message that building extremely focused numbers isn't the way to be the best general "skill monkey" in 5e. ;-)
It's hard to call something easy when most PC's would fail a roll more than half the time because they need high level proficiency and max ability score to get to that 50/50 roll rate. People are arguing extremes instead of typicals here. The table I gave used all ASI and no feats. More players are more likely to invest in combat that skill proficiencies.
Having a team of characters means having more likelihood of a better check at any giving task but nothing to the extremes of huge bonuses against everything.