The mute tool is streamlined because events are muted/unmuted as soon as you marquee-highlight them.
The eraser tool is different in that doing the above action will only select the events, then you have to click on one of them to actually delete them.
If you think about usefulness, like when you want to remove tiny accidental snippets of events that were left over from cutting and editing, it’s much quicker if it worked like the mute tool – ie. draw a marquee around the events you want to delete.
If it worked like the mute tool, you could just draw a marquee box around them and boom - they will be deleted immediately.