If this is true what is Mozilla's business making niche feature requests to other companies products that they don't own? Is the plan to do this kind of advocacy for other products?
I think it's fair to call out that Slack isn't a platform for interacting with strangers, nor the right tool for discussing a topic that would get you in trouble if e.g. your government saw your messages. But it's okay to just say, don't use Slack for that kind of thing; there's already other E2E encrypted messaging apps, and there's better platforms for managing communities of strangers where you have bad actors (who you can't deal with by contacting an HR department).
Isn't a better solution to have per instance administrative controls? Default to allowing blocking but allow companies to disable that feature. Make it clear to users in the UI when this has been done so they can complain if it's not appropriate to disable it.
Not exactly true in companies, where you're subject to the whims of HR department eventually, maybe, probably not deciding to fire someone abusive. In the mean time you're subject to abuse over and over again. Great you get lots of evidence to give HR, but in the mean time you're still subject to the abuse and taking the toll on your mental health.
Outside of a work environment, you're also subject to whatever delays the admins of your more private slack space might have around resolving the problem. Not everyone is going to be 24x7 to jump in and deal with abusive behaviour and kick people out.
The lack of blocking in Slack has been repeatedly called out by people who have been on the receiving end of abuse in slack, through both work and community slacks, and have had to deal with either major delays, or flat out refusal to deal, from the relevant authorities for the workspaces.
Which would be a great thing. Communities should not use Slack.
But also will be good a push to move those communities to a self hosted open source products like Zulip [2], Element [3] or Rocket Chat [4].