To what extent can the national team manager (Poch or whoever replaces him) even influence the deeper cultural and institutional shifts needed for talent development?

So it's probably a no brainer that the USMNT's biggest limiting factor is the lack of youth development and grassroots institutional support. So how much can the senior team manager even influence those aspects? Is it really worth it to keep cycling through prestigious managers in search of the elusive solution when the root problem isn't even with the senior team manager?