I don't know what to do to convince you that this has been the trend over the past 10-12 years. You saw it in Miami, you saw it in Boston, You saw it to a lesser extent in LA because the lakers did trade for Kobe but the 1st 3 championships were because of Shaq and he was a free agent signing. You saw it in Detroit. And Miami again with Shaq
Part of the problem is that there isn't a unified trend that I can identify.
Boston traded multiple lottery picks and assets in a free market deal for two veteran studs in Garnett and Allen and added them to their borderline HOF swingman in Paul Pierce. That was tanking and then using assets developed through the draft (lottery picks, Al Jefferson, Gerald Green, Telfair, Gomez, etc.) to trade for stars.
Miami was a totally different situation where three players conspired to have 2 of the 3 leave their current teams and sign in the same place while they were currently under contract. Then they executed that leaving their current teams little to no leverage to shop them ala Carmelo or Dwight. That was simply clearing cap space and allowing collusion to play itself out.
LA acquired Kobe in the draft and is the only team to ever control him since he was an unproven upside play on draft day. He was the building block for their recent championships. That is no different than the Bulls acquiring Scottie Pippen in the draft (through trade) or Seattle acquiring Ray Allen by draft day trade or Dallas acquiring Dirk by draft day trade or Minnesota acquiring Kevin Love, etc. Going through the draft is more similar to Boston (had they hit a home run on one of their high picks during the lottery seasons post-Antoine Walker) but is fundamentally different than the Miami model.
I agree that stars are moving themselves more often today which is why I am excited about the idea of recruiting Howard + 1 to Atlanta as an approach to build a contender here. That is why I am willing to deal for Howard without an extension. If he resigns and recruits a buddy, then we are golden. If he leaves, then we go to the lottery. Both of those ideas are superior for me to today's roster + 2 Ibaka level players.