Without seeing what it looks like, we can't tell for sure.
Breakaway tabs are certainly very manufacturable, yet not all manufacturers will do it. Some of the very affordable Chinese ones don't like it, or will at least charge extra. Unless the board becomes very unstable mechanically, I think it's not a problem of manufacturability as such, but just not wanting to do it. A lot of 'unnecessary' drill hits for perforated lines reduce tool life and rise costs.
Best to ask explicitly.