Well, another obvious con on the serverless side is that it doesn’t cover all languages. Php for one has a hard connection to the underlying system in the form of required extensions that belong to the interpreter. Exposing the interpreter setup to the serverless user is a risk, you can’t offer a one size fits all setup and on the web application side of things, the fact that pHp ties into another server(apache directly or through nginx) means it’s not as easy as just running code.

Also, serverless comes with vendor lockin, period.