I get too many emails. Its more than I could ever hope to keep track of. So I don't read most of them. So I never know what's going on.
I'm sure this was more manageable in the past but I can't really remember how.
Me, now: Everyone please toot about your cool events and calls for contributions and band camp releases and other things I should know about!
Me, if this was actually done at scale: 
Maybe the problem is a sorting problem. Like, if I could have a calendar of upcoming bandcamp releases as a layer on my evolution calendar, I'd look at it sometimes and so some add-to-wishlisting. And same with concerts and other stuff. An auto-populating calendar that allowed me to say yes/no/maybe and hide layers based on response...
I realise I am now describing an idealised version of Facebook - or perhaps the Facebook killer. The only thing good on that site are the events.
Activity pub could totally do some sort of federated event calendar, though, right? Follow the bands you care about and option for releases and geographically filtered concert dates?
Follow local venues.
Follow local clubs and backspaces.
Get some kind of calendar app that keeps track of your indications. That can also import and export caldav to/from a server so this stuff also shows up on your other calendar views.
@celesteh There was event support in OStatus and GNU social, with RSVP and everything.
@celesteh Not sure if Masto ever implemented support for it.
masto skipped a lot of good things in ostatus and now don't even bother to federate with it.
@celesteh
There is @mobilizon
for it. Its basically federated events on Activitypub like you described. It also has groups support.
@msavoritias @mobilizon I'm definitely going to check this out
#Mobilizon is the answer! https://joinmobilizon.org/en/
@mobilizon
Mufo performers, musicians, et al; send me your mobilizon accounts!