We watch games for the players. We don't watch games for the managers or the owners. The players are the performers, they are the stars, and of course they have power. And the more charismatic they are, the more power they have. That's the nature of any entertainment business. This is inescapable. Nobody goes to a football game to watch the manager of a football club (except perhaps the fans who have an absent father complex, but that's a different discussion).
The lead singer of a rock band has power. Nobody gives a fart about the manager of a rock band (although the manager of the rock band is actually a very important part of the band, and in some situations, he can make or break the band).
So, in my opinion, it is completely meaningless to talk about "player power". It is just meaningless clickbait that some journalists have created. The only way the players wouldn't have any power is if they were interchangeable, nameless robots. We wouldn't want that.
If a manager is a capable manager, then he would want strong characters under him, and he would still be able to manage them and create something great. If he can't, usually the reason is that he is not a good manager. And here, I am not talking about football managers only, the same is true in any business.
Saying that player power 'isn't a thing' is just nonsensical and smacks of you not really keeping up with the times. It was always a thing and has only become worse in these modern times of social media where every tweet is dissected ad nauseum.
I could go on at length about why you're wrong but i'll just leave my argument to the words of Alex Ferguson
“If the day came that the manager of Manchester United was controlled by the players—in other words, if the players decided how the training should be, what days they should have off, what the discipline should be, and what the tactics should be—then Manchester United would not be the Manchester United we know,” he said.
“Before I came to United, I told myself I wasn’t going to allow anyone to be stronger than I was. Your personality has to be bigger than theirs. That is vital. There are occasions when you have to ask yourself whether certain players are affecting the dressing-room atmosphere, the performance of the team, and your control of the players and staff. If they are, you have to cut the cord. There is absolutely no other way."
"It doesn’t matter if the person is the best player in the world. The long-term view of the club is more important than any individual, and the manager has to be the most important one in the club.”
Now read that and tell me that Fergie would have handled Sancho any differently than Ten Hag. Ten Hag even gave Sancho a period to get himself together but still didn't take it. Fergie would have kicked a boot at Sancho's head and he'd have been out of the door faster than you could say "Playing Playstation at 4am". The only difference is that Fergie was doing it from a position of strength, whereas Ten Hag wasn't.
Plenty of players fell foul of making the mistake 'in Fergie's eyes' that they were bigger than the club, Ince, Beckham, Stam, Keane and even Pogba aided by Raiola.