I might make a thread about this later.
The problem is that there are two ways to interact, with explicit mechanical support, with the world. Either skills or explicit abilities (these being class abilities or spells).
Skills in D&D are both weak and they do not scale properly. Sure you (slowly) improve the probability of success, but your skills never improve in impact. You don't get to do cooler things as you level up unless you get support from elsewhere.
So the D&D team is effectively saying, by making skills pathetically useless, that you can either do things well (class abilities) or do things badly (skills) and class abilities are inherently more complicated than the skill system.
Imagine if the skill system instead was tied to a coherent system designed around what characters can do, rather than being focused on how likely they are to succeed. At that point you could have a character who is both competent AND simple.
This does not even require mechanical things like Skill Feats from Pathfinder 2E. It can be done easily without adding any mechanical complexity. Look at systems that have solved this, like Icon. In Icon all skills have the same underlying mechanics and as you level up not only do you improve in your skill modifiers, you also get actively better at using them.
D&D only gives this type of explicit power to abilities, and new abilities imply new rules. Therefore in the world of D&D: Power = Complexity.