People here keep coming back to the social pressures of not allowing their kids on these platforms. It's one thing to give them a device for being able to keep tabs with locations and being able to get in touch with them, but once they have a device where other parents have allowed their kids on the platforms your kid will be made fun of for not being on there.
The parental controls the platforms put on there are non-existent or a mere joke at best (as the recent post about TikTok suggesting porn to minors illustrates). So a parent trying to do things then gets accused of "damaging" their kid by being over restrictive. So, again, what's a parent to do?