It must be remembered that comedians of this ilk (it's that word again!) learned their comedic skills before movies were ever thought of, on the stage in live performances, sort of like folk msusos... :-)

Groucho had a good radio career, he was a fast wit with words in a live situation.

Also many comedians of this period made a living for 30 years with about 20 mins of material: along came a visual medium and sucked their life work away in one go, so they had to keep on making things up without the ability to hone it over years.

Very few live comedians were able to make a successful transition to the movies.

The best movie Woddy Allen ever made was that thing where he was an ant...