I would argue that the architectural implications of using a "run individual functions on a remote pool of computing resources and build your client application

I would argue that the architectural implications of using a "run individual functions on a remote pool of computing resources and build your client application around this pattern and only pay for the exact amount of compute time you use" is not sufficiently covered by the term "managed". I think there could have perhaps been a better name than "serverless" chosen, but that's the name enough people have agreed on to use when talking about this specific architecture that it would be difficult to use another one.