Were they common? Well, just look at the GameBoy pocket. At the time it was designed (it released 7 years after the original GameBoy) there were a lot of people at Nintendo who wanted to get rid of the port entirely because it was barely ever used. They ended up compromising by using a different, smaller, cheaper port that needed an adapter to work with the regular ones.
Which was kind of a pain for some people because the GB Pocket and Pokemon both came out in Japan in 1996 lol.
Were there other uses? Yes.
Were they common? Well, just look at the GameBoy pocket. At the time it was designed (it released 7 years after the original GameBoy) there were a lot of people at Nintendo who wanted to get rid of the port entirely because it was barely ever used. They ended up compromising by using a different, smaller, cheaper port that needed an adapter to work with the regular ones.
Which was kind of a pain for some people because the GB Pocket and Pokemon both came out in Japan in 1996 lol.