Yes ex-developers promoted into positions in that committeer Hierarchy will do less development and more "steering". But they know that - as do editors at newspapers. Junio Hamano even writes interesting notes on it. But again only a fool hires an illiterate for that position. And only a fool creates a seperate parallel organisation to keep an eye on / communicate with, the software teams. Once upon a time there were few developers and software was a strategic project to reduce costs. Now it is everywhere - like literacy, it infects everything with outsized leverage. And you cannot maintain two parallel organisations - one that does the business and one that then goes off and imements it. It's insanity.
Again I like to use the newspaper analogy - it makes it clear where we need to go. It is probably true that project managers are needed for an organisation that is illiterate at the board level, in the sales force and in the marketing dept.
But companies like GitHub are not showing us how to overlay old illiterate management styles on company with mostly developers - They are showing how to run a company when everyone in it can read and write.
Honestly I do not know how companies prior to printing press organised themselves - but I bet it was different after literacy was widespread - and I bet the old companies did not survive the new