That was 16yrs ago. Just because he did that once doesn't mean he can do it again. He tried it with Kyrie and Hayward and it didn't work out and then he brought in Kemba who turned into the worst contract in the nba. No one is saying Ainge hit on things but we also can't just completely ignore the misses as well.
He also built the current Celtics team who has been a perennial contender in the EC for the last what 5-6 years? Winning a championship in the NBA is hard as ****.