I think its a naive attempt at describing worker processes and application scope. if you have a worker process per endpoint which is common with .net apps and lots of endpoints, its quite hard to balance resources. This is true. In PHP, none of this is of consequence.

Now I've got a tiny (280mb deployable, 5 hosts, 37 application pools, 5000 in flight requests 24/7) behemoth on my hands and I can testify its an arse pain to manage resources.