This is stupid.
People on the internet are just as capable as being deceptive or cruel. In fact, it's so much easier! You're also just as capable of growing a part from them (happened to me many times), but if you happen to move away from an IRL friend, they can just easily become an internet friend. And it's super easy to find people who share similar interests as you (in mass) like on this site. So thinking that everyone irl doesn't share similar interests in you is just dumb, they don't, it's just they might not express it and so they're harder to find.
Positives of online friends are they're so easy to meet and if you're socially screwed it's a lot more comfortable. But with a real life friend you can do all the things you want with them on the computer as you can with online friends, but you can do more (irl stuff). I remember a time when several friends of mine would all play online games, that shit was fun as hell and I miss that soo much. But I've also done the same with internet friends.
Personally I think IRL friends are better but that's because I'm not afraid to make irl friends (but I'm a bit more on the introverted side).