Most of the top clubs have a footballing structure that doesn't give managers full control of transfers. Even great managers who can handle the coaching and on-field aspects can be bad judges of transfers - Conte 2017 was an example, Tuchel viewed Lukaku as a good fit after Haaland and Kane.
I think the structure is fine but their strategy of buying expensive young players has cost us several years when the Premier League has had the best buying power in Europe.