Of course age is the most important thing with prospects, was just reacting to the statement, which said nothing about age.
Here's one: Mancini had a 691 OPS in high A at age 22. He reached the majors 2 years later. And no, it doesn't matter he was an 8th round pick, draft status is meaningless at this point.
It no longer matters as far as his performance now. It does matter when evaluating the pick. You shouldn't be getting role players with top 5 picks.