Yes,but smaller market share means less optimistic future

Optimism in terms of user adoption? Sure. But these are your choices. I understand your apprehension. You can choose the “easy” button and let the corpos continue to silently abuse you, and be complicit in their abuse of others, or you can take a few minutes to learn something new and convince others to do the same, and try to be part of the solution.

continued to email my old email address, too

Yep, people did that to me too. I deleted the old email address. Their IG and FB messages also stay on unread. Some of them I even blocked. When their emails bounced and I didn’t give them a new one, they logged into Signal and started messaging me there. When my Dad would forward me whatever new business scams he would come across, I would ask my Mom to ask him to send them over Signal and then I would entertain his delusions.

Personally, I find switching messenger providers to be more difficult than email

Depends on which one, but I will respectfully disagree.