The main reason many sub-communities are stuck on Telegram (and Discord) are the public group chat/broadcast channel related features. Signal still has a 1000 member group size limit, which is more than enough for a “group DM” but mostly useless for groups with publicly posted invite links. Those same groups would also much rather have functional scrollback/search on join instead of encryption.
Most paid certs aren’t worth much anyway. Payment and delivery info for DV certs isn’t validated by anyone, it’s literally the same concept as Let’s Encrypt. OV and EV are the only ones that theoretically have any value, but nobody is using those ever since they got rid of the URL bar labeling; even Amazon is on DV nowadays.