'but he does not control the club strategy, no lower level director (and that's what he is) would do so.'
are you out of your mind? you're comparing a football club to any other business. a manager at a football has 100 times more responsibility and control than a manager on the high street. can you not see that? when wenger first came, he probably did not have control over club strategy or control off the pitch, but over the years he won trophies and gained the trust of the board, and now he clearly has. you earn the trust of the board and wenger done that, so now has full control. the board trust him and if you cant see that then this debate can go no further.
was it wenger who advocated this youth project, yes or no? yes. therefore he has controlled the club strategy. something you said he cant.
also from the link you posted, ""It looks like managers have less of a say but I will go on my way if that happened.". If that doesnt state that if someone blocked him doing what he wanted to do he would walk, then i dont know what is.