This is why Facebook ended up being the tool of choice. Stay in one app instead of logging into 2 and checking your email and a website. I'm only surprised that 1-3 can't all be done via Meetup.
The point seems to be that you can pick whatever service you want and will still get the information because it’s repeated across channels. The manager needs to post to all four, but everyone else picks one.
The email list is probably the single most important part of the tech stack actually.