For millions of years kids never had running water in the home and they grew up just fine. In fact they grew up with fewer cases of depression etc. I’ve got a kid and I don’t let them use a sink, bathtub, or toilet unless I’m there interacting with them, doing stuff together. Maybe I’ll let them watch for 15min for a job well done but not for hours on end.
Here's what I think, but every parent needs to decide for themselves: like it or not, the Internet is an integral part to socializing today. Not allowing your children to socialize this way will hinder their social development, especially when you have no control over them in 0-18 years from now. They need to be able to learn about how to behave on the 'net from a young age, with good supervision and guidance. Sometimes it's good to prevent a child from doing something harmful, and perhaps limiting their screen time in certain ways is necessary, however an extreme version of what you say (15 minutes) is definitely going to hobble their social lives at some point.