"No one owns the whole stack" - depending on the nature of what you are integrating this can either speed things up or slow things down

"You pick your "main" software, and customize it with third-party services" - not much difference monolith vs microservices

"None of it runs on your premises" - totaly unrelated to monolith vs microservices

"No party is willing to expose much more than an API" - again consuming an API can actually be easier in monolith vs microservices