If you’re going to be on Internet, CR is probably one of the better places to be.
But neither one is l’chatchila, imho. And anyone who thinks so is fooling themselves, imho. But we don’t live in a l’chatchila world, and everyone has to make their own cheshbonos.
That involves considering what your alternatives are. That is different for each person. There may be some people who would be learning Torah. They should not be here. There may be some who would be on other sites online. They probably should be here (depending what those sites are). There are some who would go out of their minds because they need the outlet because their jobs are boring or they live or work by themselves, etc. They probably should be here, unless they can find a better outlet.
Additionally, as in any other decision, it also involves considering the maalos and chesronos. Some people may feel that the site either gives them chizuk and/or gives them the opportunity to give chizuk to others. Some may feel that they learn more Torah as a result of the CR since it gives them the impetus to look things up.
Those things should be weighed against any potential chesronos. But anyone who thinks there are no chesronos is fooling himself, imho.