Lets see one by one your examples. The Sixers were a fluky Nephew shot away from going to the finals imo. They would've beaten the Bucks(i don't trust the Bucks and Bud at all), They have a real shot this year imo.
Brooklyn is in a big market unlike us, can't use them as an example
Bucks were just lucky but they f.cked up by having a fed ex guy for a GM because their owners want to meddle
Boston is one legit big away of true contention but they have the talent in place to become true contenters in the not distant future, young players need time to evolve even if they are top talent and i'm pretty sure Tatum is gonna be pretty great and even Brown, i'm not sure i can say that about our guys.
Toronto has probably the best GM in the NBA and a top 3 coach imo and they lucked into taking nephew.
Charlotte have GM MJ, nothing else needs to be said.
Orlando is the 8th seed for a few years now, they dont draft high, they were the definition of treadmill team, maybe they can tank properly this season.
Cleveland used their tanking lottery picks and got Love and won the chip, you forgot about that.
A team with a competent GM can tank and go straight to contention. We're not talking about incompetent organizations(Knicks,Bulls)