The one vulnerability to this model is integrations. Spam filters have become good enough that I seldom see true spam in my email. It's all the ham - automated garbage, purchase confirmations, and newsletters that I've been opted into that clog up my box.

If Slack admins go crazy on integrations, you can still get a lot of low-value notifications. In our instance, we only run integrations into topic-specific channels (such as a channel for system notifications) so it's manageable.

But I can see that changing as the scope of integrations grow.