Yes, I program for a living and have for 30 years. I get the importance of incremental compiling.90% of programming is debugging. Well, something like that. A lot. A programmer trying to chase down a bug will tweak one or two source files and try that to see if it fixes the problem. This can go on all night. This is where the compiler gets the most use. That is why it matters.
What I don't really see is how/why the M1 would specifically be better at it than any other platform. What strength(s) is "incremental compiling" playing to or what weakness(es) is it exposing?
Somebody above stated the "M1 was a giant leap forward" with respect to incremental builds and I don't see technically why this would be the case. Faster SSD performance? Closer memory? Larger cache?
BTW, I've found the longest part of incremental building is many times firing up the build system to detect dependencies and what's out of date and needs to be built. (Make is particularly slow at this unless you turn off implicit rules).