I think it's more accurate to say that it allows you to borrow X. It's very true that it helps to bootstrap your own product and eventually if things work out you can bring X in-house.
My worry about everything-as-a-service is that until that point, each different service that you use is an another vulnerability to your product. This goes double for specialized services like AI, where unless you already have experts in that field, you're unlikely to have the expertise to replicate the service in-house. (Although by that same token, in this case without the service you couldn't provide your product anyway.)