You are determined to argue against thing neither said nor implied. The first post in the thread makes the point that Ducati didn't try very hard to keep Lorenzo on the team. Their disappointment in his efforts and his lack of team spirit was pretty clear.
All of us Monday morning quarterbacks can now say in retrospect that he should have stayed, but at the time he made the decision to look for a better fit, the consensus was it wasn't going to work out. It was (to him at least) an untenable situation, where there was bad blood between him and Dovi and he hadn't any faith that Ducati was capable of making the bike more suited to his riding style. Gigi was pushing for the factory to back Lorenzo and the factory said, no, we're backing Dovi and clearly that wasn't acceptable for Lorenzo. The more you think on it, the more it becomes clear that Lorenzo came on the team expecting his pal Gigi to propel him to top rider status and that didn't pan out.
He started with top rider status, there was debate as to whether iannone or Dovi should be his team mate if you recall. Dovi greatly out performed him in 2017 pure and simple.
The only thing, and reportedly a cause of some of the rancour between him and Dovi, was whether he was a more significant contributor than Dovi to the quality of the bike with Gigi apparently on the Jorge side of the argument. At the moment there seems to be an impasse between Dovi and Gigi with Dovi back to the old make the Ducati into a Yamaha thing and Gigi apparently of the opinion this can’t be done and/or it being a bad idea to attempt this.
In the end if Jorge has made 2 ego driven major career decisions that is on him, fan of his though I am, and similarly if his decisions were mainly on the basis of the money on offer. Rossi didn’t repeat his Ducati error. It is also likely once it became obvious Rossi was on the decline Yamaha would have backed Jorge who did after all win them their last 3 titles, with anything held against him over 2015 forgotten.