I think there's a degree of truth in what you say, especially when it comes to the cliché that PSG is difficult to manage. Tuchel, as you point out, regularly changed systems and his players accepted it. Pochettino, likewise, prepared specific tactics for the Champions league knock out ties that were executed well until the City games. It is an easy get out to claim that the PSG squad is unmanageable and no coach can control it. However, its a slur on the professionalism of PSG's players. One that does not stand up to evidence. PSG's players have repeatedly demonstrated a willingness to be tactically flexible and to follow instructions. Blaming the players is just a way of excusing Pochettino.
The squad, as you say, probably needs a bit of dusting up. However, I think most people's fire for Poch comes from the fact that very few people would pick Lille's squad over PSG's. Lille has done an amazing job this season. Don't get me wrong. The squad has been superbly assembled and they really bounce off of each other: The weaknesses of one are compensated for by the strengths of the other. However, for all of that, people still expected (IMO rightly) Poch to be able to overcome a one point deficit over the months he has been PSG coach. The criticism of Pochettino may be overblown but its not unwarranted.