> Through all of this, no one has cogently explained why Altman leaving is such a big deal.

Pure f***g Greed. He is basically a front-man for a bunch of VCs/Angels/Influential Business Folks/Shady Investors/etc. who were betting on making big bucks through him.

Unfortunately, Ilya and his philosophical/ethical/moral stance has gotten in their way and hence they have let loose their dogs in the media to play up Sam Altman's "indispensability" to OpenAI.