I think this debate is premised on the idea that tanking means "being awful on purpose." While that is the literal definition of it in the sports world, in practical terms, it's not really what you mean.
What I think you mean by tanking is "recognizing that we're nowhere near a title contender and dumping all the ballast that isn't going to help us get there, with the happy side-effect that this will allow us to get better players via the draft."
So you never try to lose on purpose. You don't have to; as someone said further up-thread, even Kevin Durant didn't turn his team into a contender overnight. The only time that happens is when the team already has significant veteran assets in place, as when the Spurs added Duncan to Robinson or the Celtics added Larry Bird to Archibald, Maxwell, and Cowens. We don't have that, so just let the kids play and take their lumps.
If you get lucky, one of them develops into a star. If you get really lucky, you pick up another star with the draft pick they helped you get by being young and lumpy. Once you have two stars, you can generally work out a deal for the third. (Three stars is always the magic number in the NBA. You can do it with two, but only if they're dominant.) Once you have three stars, the role players will fall into line to chase rings.
Tanking is step one in that process, the state in which everything on your roster that isn't one of those three stars, a young player capable of becoming one of those stars, or a draft pick theoretically capable of doing so, is expendable and possibly counter-productive. So you maximize your efforts to play/acquire young assets and minimize the veteran role players-- because they're only getting in your way. You can't win (big) with them alone, and they're utterly replaceable once you get to the stage where you need them.
(Rondo complicates things, because 1) he's good enough to be one of the stars already, but 2) he's injured and thus a question mark, and 3) he's honestly not the player you'd prefer to build around for several reasons-- mainly his poor shooting-- but 4) you're still better off with one star than zero, so 5) if you trade him you must get a high likelihood of another star in return. For the moment, I'm leaving him out of this analysis, because I simply don't know what we have in him or whether we're likely to keep it long-term.)
The conclusion is the same either way: you don't ever stop the kids from playing well. Once that happens, you're on the road from step one to step two, and winning games starts being a positive thing again..