Everything that needs to be rolled is related to an ability. It has to be, or the system breaks down! In some circumstances you might want a pure randomiser, but generally if the characters ability or skill is involved the DM is basically just expected to make a best fit and ask for a roll.For what it's worth, the Basic Rules present checks in this order:
" . . . The DM calls for an ability check when a character or monster attempts an action (other than an attack) that has a chance of failure . . . "
" . . . the DM decides which of the six abilities is relevant to the task at hand . . . "
" . . . Sometimes, the DM might ask for an ability check using a specific skill—for example, “Make a Wisdom (Perception) check.” At other times, a player might ask the DM if proficiency in a particular skill applies to a check."
So yeah, if you've been asking for "Perception" checks, you've been doing the badwrongfun.
Interestingly, they suggest that attack rolls don't follow the same rules as ability checks. But the attack roll uses a relevant ability and adds your proficiency bonus if you're proficient with the weapon...so I'm not quite sure what that attack disclaimer was about.
Leave it to the people who played 3e and 4e for years and years.
And somewhat less than 90% of the time, the PC will actually have the proficiency the DM is asking for. Which of these thought processes are easier?
- The DM called for a Wisdom check. I'll roll it. I wish I had proficiency in Perception.
- The DM called for a Perception check. I don't have proficiency in Perception. Its relevant ability is Wisdom. I'll roll that instead.
Linking all skills and abilities may be simple, but it creates a problem: what happens when the action you're attempting isn't related to a skill? Or worse, when it's not related to an ability?
Not being related to a skill isn't necessarily a problem. The system already allows for Tool proficiencies. It wouldn't really be a stretch at all to allow other things to apply proficiency - (Such as the soldier background to train toops). As proficiency is always the same number the system makes it very easy to handle. And of course sometimes you just don't get proficiency.
The issue with ability checks governing everything is that they're just not designed for that purpose so even if you are using backgrounds ther'es likely to be times when you just end up saying "Make me a Dex roll, plus any relevant stealth background" because it just saves time.
In Symbaroum, which does not really have skills (well it sort of does in a way but they work more like feats), there are eight abilities, and stealth and perception are separate abilities which cuts out the biggest problems.