There are a couple of different points I'd like to make. The first is to ask people to define tanking : is it tanking to realize after 100 games that you're going nowhere that year and you'd be better off bailing out and getting a better draft pick ? After 50 games ? 120 ? Honestly, if other teams are doing it ( and they do) you can't unilaterally disarm yourself without hurting your team; it needs to done by the whole league. In the absence of an anti-tanking mechanism, you'll suffer for not joining in.
Secondly, someone stated that anyone can rebuild by tanking. That's absurd. If trading people who are good this season and not much use down the road is tanking, then I think that tanking is perfectly legit. If you just finish last, without trading your one-year talent to contenders, you will have a hard time building a winner. If you trade off your current shorter-term talent for young players and picks, then you can rebuild your team successfully. The other thing is that if you trade your talent for future talent you'll also likely get deep into the lottery. Rebuilding your team through taking a step backward in order to go forward later isn't tanking and is a perfectly legitimate way of building a team. Finishing last and adding the number 1,21 and 41 picks in the rookie draft ain't gonna get you where you wanna go.