Because they risk being bullied or left out. Denying their kid a phone only works if all the parents do it.
Edit: I don't have a solution; maybe an anti-bullshit law that punishes people from spouting bullshit? (Good luck religious folks!)
But denying a phone may just replace one problem with another.
I went with FUTO Keyboard. It's the only keyboard that ticks all my boxes to replace GBoard so far.
I wish the swiping predictions were a bit better though.