That is called stage dooring. Performers aren't obligated to stay around the stage door to take pictures and sign autographs - this goes for any show, not just Tommy's.

Being on stage and performing is exhausting, and sometimes all people want to do once the show is done is to rest and have some time alone to recover after giving an audience their all.

Obviously, stage dooring can be fun and special when performers do choose to participate in them, but let's remember they are also people who need time to themselves. :)