FWIW, I agree with Hawk — don’t do this, it’s counterproductive — but I also can’t help but keep coming up with more suggestions. 
- You could use a webhook which is called on User Event, hooked to a script which uses the API to add all users to an “everyone” group.
- You may be able to use the upcoming Discourse-automation plugin to do the same.
- Or maybe even use that directly to send a reminder to people who haven’t voted in your poll.
I can actually see that last case being … not the worst? … if you use it for, say, once-a-year moderator elections or something, and send a reminder when the poll opens and again a week later to those who haven’t yet voted.
But here’s another direction that might be more appropriate for things like “a bug in the product that needs quick confirmation” — look at the Chat Integration plugin, and send to Matrix or a Slack channel where your devs hang out.
That’s because in general, Discourse excels at asynchronous communication. It seems like some of your use cases are really about immediate response and interaction, for which a chat system is better.