Ah yes, I too love free servers and bandwidth.
replyLol, it doesn't have to run for free and servers are really powerful these days (especially if you don't use a slow language). There are other monetisation strategies besides exploiting users for profit.
replyIt doesn't have to run for free, but if you're competing against anyone else running for free you've already lost the game as they suck the air out of the room with the network effect.
replyNext, text only platforms are nice, but niche on the modern internet. People seem to love multimedia which takes tons of bandwidth/cpu.
Paid for services don't mean spam free either. If it's worth people to pay for, it's worth spammers paying to get in and spam.
Then you have all the questions on what happens if you grow, how do you deal with working with all the laws around the world, how do you deal with other legal issues.
Having a site/service of any size can quickly become an expensive mess.