Nah, thats not the case. Games are different enough, and BB has plenty of complexity (often more than GG). BUT you will be correct to always choose GG if its "either or" situation (especially pre-GGST).

Since both games require a lot of commitment, when BB came out people had to choose between the two, and since GG had established player base - most chose what they knew. Which creates snowball effect. New players, considering how poor netcode is in fighting games, are better off choosing the game with bigger player base, also contributing to snowball.

Maybe now, after ArcSys got better at netcode, BB will get a chance to properly compete if it ever gets a sequel.