You don't get anything except a very small and effectively insignificant change to the ending if you get all the emeralds in Sonic 1 (you don't even get 7 emeralds) so I'd say it counts. Sonic 2 and 3/Knuckles actually give a meaningful reward for getting all the emeralds so it's worth it to go for them, even if going for them in Sonic 2 is a real pain in the butt (and the one real bad thing about Sonic 2).