Makes sense as that table keeps track of profile views. So it can get large if you've profile view tracking enabled and an active site. Cleaning it out defeats the point of it as then views would be lost. I recommend just turning off profile view tracking and emptying the table. You can turn off profile views tracking within CB > Configuration > User Profile by setting "Record Views" to "No".

If you still want to keep views tracking and only delete older views then yes that's possible using CB Auto Actions, but again kind of defeats the point of it and if you aren't using the "Views" (hits) field you might as well turn the entire process off.

I didn't understand the purpose of Views. It's not something that any of my clients use. They mostly use Community Builder to create board member and sponsor lists; some have member lists. The number of hits each profile gets is irrelevant. I don't even display it on the profile pages.

Its purpose is to provide views tracking. It's used for the "Views" (hits) field and CB LastViews Tab plugin. If you don't need any of this just turn it off.

Is it simply a matter of deleting all the records in the comprofiler_views table, or are there dependencies that I might break if I do so?

All you need to do is turn off that parameter and empty the table. That completely disables its usage. Nothing will break by doing this.