Zlatan knows how massive clubs operates, he's played for the biggest sides in every major league in Europe. The other side of this coin is if Zlatan, with all of his mental toughness, is annoyed by it then how are the rest of the club taking it and is it helpful in any way?
Liverpool fell away, in part by always championing their former players over how modern football operates. There's a real danger we could follow suit to be honest.
On the other hand you can say the biggest clubs are built or led by the people who played or spent time at the clubs.
Juventus - Their comeback was because of Conte, their former player, who played for more than 10 years and won everything there is to win.
Atletico Madrid - Their former player who won league title as a player for Atletico Madrid
Real Madrid - Their legendary player who came back as manager and won 3 CL titles. Before that their most successful period was under Del Bosque who played almost his entire career at Madrid.
Barcelona - They won 5 CL titles, 4 of them are won by coaches who were also superb players for Barca. Cruyff, Pep, Luis Enrique.
Milan - Won league title, couple of CL titles and few runners up under ex Milan player Ancelotti.
Bayern - Their president and Chairman are ex Bayern players who won everything at Bayern.
Ajax are back to CL, many of their Ex player are running the club now. They won 6 league titles in last 20 years and all of them under ex Ajax players. They won CL under manager who was assistant at Ajax
PSV have won league title and leading table under their Ex player now.
Just because Liverpool somehow messed up doesn't mean it's a failed method. (btw they were very successful with Shalkly, Paisley, Fagan, Dalglish. All successive managers promoted within).