The rise of "agile" in tech is mostly myth. There are small startups that are run as pure dictatorships and there are large corporations that have teams but they are not autonomous.
Corporations can create autonomous teams as Google famously did with its "bets" and that can result in one being successful like Waymo. However for the most part large corporations just get by on monopoly or oligopoly power, sometimes with government help.
Where tech really has a different structure is in open source software. However even there you will frequently find hierarchy over democracy.
Agile in tech failed for the same reason that drives the institutional monoculture you describe. At the interface between funding and funded, you cannot bottleneck.
So if a VC funds a startup and only one guy has access to the VC, then you are just going to have a dictatorship. Similarly if your public institution has one administrator that secures the money, then he is the man. You can see this in the diary of Samuel Pepys from the 17th-century and his exploits in sleeping with the wives of those wanting favor.