yes. no. who knows?
really, i think it depends on the kind of person you already are. for me, my social growth has been strengthened due to the internet - my social skills are fairly non-existent in a general sense (believe it or not i'm very shy, and have big self-esteem issues), but the internet allows you to establish a basis for friendship, and get past those awkward and uncomfortable -for me- opening moments/weeks/months of a relationship.
basically, the internet allows me to make a good (sometimes
) first impression and then you're stuck in my web of deceit and trickery
ahem, anyway.
my point is, for people like myself, the internet can be helpful - i'm not so lacking in social skills that i can't develop anything but 'internet friends' (which imo, *would* be unhealthy), but enough so that the internet helps to expand my friendship groups, and explore new social experiences.
for others, the opposite could occur - for the real social outcasts amongst us, then i would presume that being locked up inside all day, with other 'net geeks as your only 'friends' could not be too healthy.
some good, some bad