Moving stuff out of the standard library seems like a reason. However, I think this all is a weird mix of arguments. IMHO new process spawning is a feature and not a bug in the use cases where CGI is used. Most of the stuff is low traffic config interfaces or remote invocable scripts. There was this trend to move stuff to fcgi. We had tons of cases of memory leaks in long running but really seldomly used stuff like mailing list servers. To me cgi is the poor man's alternative to serverless. However, I also do not really completely understand why a standard library has to support it. I have bash scripts running using the Apache CGI mod.
I would have phrased it, "serverless is a marketing term for CGI scripts."
I have bash CGI scripts too, though Shellshock and bash's general bug-proneness make me doubt that this was wise.
There are some advantages of having the CGI protocol implemented in a library. There are common input-handling bugs the library can avoid, it means that simple CGI programs can be really simple, and it lets you switch away from CGI when desired.
That said, XSS was a huge problem with really simple CGI programs, and an HTML output library that avoids that by default is more important than the input parsing—another thing absent from Python's standard library but done right by Django.
I used bash cgi scripts all the time. Haven’t used a python cgi module but the main benefit of perl’s cgi module (also removed) is the query parameter parsing.
