What’s the reasoning behind lack of B/I text on social media? These are mature platforms, I can’t think of a good reason to prefer “math symbols as style” over actual B/I characters?
Abuse. Twitter/X allowed bold text recently for a few days, and a number of monetized accounts immediately started making all their posts ALL BOLD ALL THE TIME to stand out. Feature dropped soon after.
This would explain a ban on some high % of bold text in a post, not on making this % 0
My guess is that any user input goes through strip_tags() as a precaution.