ETH has been doing very well, but he's not earned the power to decide all the transfer. A well run club needs its DoF, and its recruitment team to have their input. Why? Because however good the manager is, he doesn't have the time to study all the players out there, especially someone like ETH a hand on manager working on the training pitch.
Hypothetically if ETH makes mistakes which would end up costing himself the job in the future, then he would leave the mess of his mistake for us to clean up just like previous managers. ETH may be building a more solid foundation than Mourinho LVG Ole, but he's not yet build our team as consistent big title contenders. This team ceiling is not exactly on different level. Winning League Cup or even adding EL and FA Cup this season is high enough to position to start messing around. You look at Liverpool and you see how easy few mistakes can set a top teams back several level.
Perhaps expensive signings, the manager should have the final say because he has to put his job in line. For cheap squad signing, I find it difficult to believe that professional scouting team to find better forward than Weghorst.