I think you're oversimplifying. There's a world of difference between "all notification queues decrease productivity" and "some notification queues can decrease productivity in some cases".
Seems something of a divide in interpretation of comments here between people who get subjectivity and people who insist everything is necessarily a binary.
If you think your employees would be less productive if they didn't have a queue of work items to address and co-worker comments to look at and respond to... let's just I wouldn't work at your shop. You running a room full of air-gapped code production units or something?