Doing a silent movie is harder than a sound film not just because the music is always there and so there is a lot, but also because it has to have a constant presence without being annoying. It is narrating the events along with the scenes, and sound film music doesn't do that at all but rather highlights emotions or images and scenes. I have wondered if I could do one but have not tried. Many old silent film scores were just compendiums of tunes in various moods, but to actually compose and/or improvise one is an extreme skill.
By the way my favorite silent films are Buster Keaton - Sherlock Jr. and The Cameraman are fantastically good and still hilarious.