It's not really true though. Incremental expansion doesn't actually require more heads if the compute is uniform.
I should really have mentioned storage. Networking is a vendor-imposed shitshow, but storage, storage is next level. It's almost like the vendors in 1995-2020 actively built their products around spite and hate for their customers.
To me it is interesting that despite the massive economic advantage that vendors _should_ have, they've made their products so unusable that people will pay 3x-10x more just to not have to deal with them, which is what cloud amounts to for enterprise customers.