i is for index. j is simply the next letter and we’re too lazy to think up something meaningful

Consider the opposite. Every single person on the planet making 10 posts per day. It would be like Facebook on super meth.

You don’t let pedophiles babysit your kids, and you don’t let Facebook federate with your social network.

The same reason that a lot of crosswalks have fake buttons. So you feel like you have control.