As a reviewer, I often have multiple comments to add to a PR, sometimes even more than 10. It would be very helpful to be able to group them and submit them all "in one go".

This way the review process is much more clear, and as an author you don't just hang there thinking "is the reviewer done with his review?". I would also guess that this gives some sort of an incentive for reviewers to get their review done and not just leave it up there. Oh and it also prevents spamming the author with multiple emails / notifications for each comment.

I've recently discovered that this feature exists on GitHub (attaching a screenshot), but honestly I felt the need for it long before I discovered this.

I would expect this feature to work for both code-comments and multiple "general" comments (unlike GitHub where you can only have one "general" comment per review submission).