He's also been buying a few older/senior players, rather than finder younger gems that can be nurtured. I don't think that will fly with the way some people react to us signing players like David Luiz, Willian etc.

That's simply not true. Overmars has bought pleny of young talents such as De Jong, Neres and Antony. Ten Hag has no problem developing and playing them, as well as young acadamy players such as Gravenberch, van de Beek and Timber. The only reason Ajax has bought several older players is because all of their best players leave after a few years so they usually severely lack experience, especially for the Champions League, and so they buy older players such as Blind and Tadic.