It's not strictly required by the definition of open source, but....
A) If you don't provide builds and successful building is more involved then ./configure && make && make install, then you're pretty user-unfriendly.
B) If you aren't providing builds for target platforms then you probably aren't building for target platforms, which means part of your software has zero test coverage. Again, not a requirement, but it's fair for people to count that as a negative.
I used to distribute open source bindings to a commercial+proprietary library. I couldn't provide builds because I didn't have a distribution right to the proprietary license, even though I could test it on my own copy.
These days I'm having a tough time providing a build for macOS because my Python extension uses OpenMP, and there are several different ways to get OpenMP for that OS. See https://pypackaging-native.github.io/key-issues/native-depen... for details, including how PyTorch vendors Intel's libiomp while Scikit-learn vendors clang's libomp or GNU's libgomp.
Rather than deal with that mess, I provide source, and test with libgomp.
This QT version or that? Hunt down some weird dependency. Find that that dependency clashes with a more recent version, but you can't downgrade. Oh, oops your app depends on a quirk in glibc v x but your system only has v y so now you have to figure out how to run two different glibc's without conflicting with each other, and better not make a mistake during that installation or your system may never boot again.
Complex software can be quite a pain to build properly, more-so if you want to target multiple different architectures or operating systems.
But it is required by Free Software licenses. GPLv2 §3[0]:
> The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable.
GPLv3 §1[1]:
> The “Corresponding Source” for a work in object code form means all the source code needed to generate, install, and (for an executable work) run the object code and to modify the work, including scripts to control those activities.
If you are distributing someone else's GPL code, then you must comply with the license and provide build scripts etc.
If you choose to release some code under the GPL that you yourself have written, but do not feel like even writing a Makefile, that's totally fine.
I mean, yes, that's technically correct. But I'm not sure how useful it is? What is it adding to the discussion?
The holder can change licencing for new versions of the software afterall