The question might boil down to use case. If the use case is “in this file, change all spans with class foo to divs with class bar once ever”, probably both tools will work.

If the use case is “every day, download this file from a server and process it using pre-defined text editing commands”, multi-cursor doesn’t help you in any way that I can see.

I admit there’s a huge overlap in use, but when someone asks for macros and a product person says “how about multi-cursor instead?” I think it’s fair to raise the cases where someone asking for macros might actually want macros.