I think, and please take this with a grain of salt because I have 0 inside knowledge, that Arsene is the one holding the club back from really pivoting to the Dortmund/Napoli model.
I wrote a long post a while ago about whether or not Arsenal should embrace selling culture and become a Dortmund/Napoli club. Basically the club would focus on buying players in the 18-25 age bracket, train them up and then start flipping them.
The problem as I see it is that up until a few years ago you could still find promising players and sign them for (comparatively) not a lot of money. Things changed when ManU signed Martial for a huge fee.
Besides, if Neymar is going for more than 100m, if Coutinho is going for more than 100m you could see a scenario in which … let’s say Watford wanted 30m for Richarlson.
Arsene doesn’t want to pay those fees. Hopefully the introduction of people on the business side who outrank Arsene in terms of pulling the trigger on signings will help. I’m very skeptical, unfortunately.