I honestly think it more has to do with the fact that the coaching candidates are so uninspiring right now.
Bayern, Liverpool, Chelsea, and Manchester United (potentially) all have jobs available and there are no top candidates really looking for those jobs.
If Xabi Alonso or Klopp wanted any of those jobs and wanted control in building the club, they would get that. But when the available candidates are all have question marks on their resumes, they're not going to get the power that a rock star coach would get.
As for Poch, De Zerbi, and Tuchel, sure they want control --- but all those coaches werent exactly performing well with their clubs. If they were having massive success, I'm sure they'd get more power and control within their clubs.