One of my favorite moments was when my non-developer friend at a tech company asked me what scrum masters did because she could not figure out what the scrum masters did at her company. I told her the answer which is nothing.
Schedule meetings, move tickets around, moderate meetings, call more meetings, scold misbehaviour during meetings, help management with their stuff(secretary/personal assistant?), scold other teams for not helping out in time, question about stale tasks(tickets), act as coordinator of news/requests/demands from other teams, attend all meetings which involve tickets, coerce/seduce other teams to deliver something early because our team has messed up, promote more scrum agile topics. At least that is what I observed at my work. They indeed do a lot of work but often not well defined.
Scrum Master is a terrible name though, in games we call this role a Producer but I agree they do a lot of often unseen and very useful work.
I cant tell if you're making fun of or trying to justify scrum masters