I get that there is a minimum and I get that superstars aren't lining up to come to the D. However that doesn't mean you can just fukk up over and over again and it's acceptable.
What's the reason?

The reason is this nikka turned what could have been a dynasty back into a lottery squad with bad decision after bad decision. I give him 0 credit for drafting Drummond. It doesn't take much guile to draft a consensus top 3 talent at the 9 spot. It's not like he found Drummond on some Manu/Parker type shyt. He just got lucky.
Exactly what good has he done? Traded away a bad deal that he was responsible for? Took advantage of other teams passing on top talents in the draft?
Just because other GMs are bad doesn't mean I should tolerate Joe D's ineptitude. That's like saying "

Hey other kids parents starve them and burn them with irons, you should be happy that yours feed you garbage and beat you."