Like, there are plenty of musical pieces I can play; that doesn't make them not art.
I enjoy drawing though I am not great at it; that doesn't make my drawing not art... that just makes my drawings mediocre art.
So, at the very least, I don't think that's a sustainable definition of art.
For what it's worth, if you can accept that argument, then you might want to go a step further and question what does qualify as "Great art", and I feel like it's not just way out in left field to say that in addition to execution, the difference is in how it treats ideas.
Hypothesizing that people are responding to formal ideas would give at least an account that avoids a redunctionist and cynical "the emperor has no clothes" account of why people who seem to know a whole lot about their respective art forms like things like free jazz, abstract paintings, and strange performance art.