Songs can be autobiographical, but Boston’s Rock N Roll Band was not one of those. Tom Scholz basically created Boston in his basement, and that’s not mentioned anywhere in the song. He chose the time honored profile of a hard working band paying their dues on the road for that classic.
Scholz tells all in this interview.
To further de-mythtify the song, the crowd noise wasn’t even from a Boston show, it was from a Wings concert.