D&D 5E Using Ability Check Proficiency (DMG 263)

[Charlaquin]

I've also considered removing the notion of skills altogether and just counting all the other character selections to be proficiencies that you can add to a situation if it's justified. If you're Wizard, your class gives you proficiency when trying to discern arcane knowledge with an Intelligence check. If you have the Soldier background, you have proficiency on the Strength check to knock a guy over. If you know Elvish, you have proficiency in the Charisma check to hail the elven king. I think it could be a nice, rules-light alternative, but it's certainly a departure from the usual rules (so I'm a bit reticient to add it to my regular games).

It pretty much worked this way in the early 5e open playtest packets. They were still called “skills” and still had names like they were discrete things, but there wasn’t a fixed list of them. Theoretically any specific task you wanted your character to be extra good at, you could take as a skill. Worked beautifully in my opinion and I was pretty disappointed when they decided to make an official skill list.