Packaging is hard. Packager-friendly is harder.

So, a concrete example: MonoDevelop. MD in Debian is pretty old. Why isn’t it newer? Well, because the build system moved away from a packager ideal so far it’s basically impossible at current community & company staffing levels to claw it back. Build-time dependency downloads went from a half dozen in the 5.x era (somewhat easily patched away in distributions) to over 110 today. The underlying build system changed from XBuild (Mono’s reimplementation of Microsoft MSBuild, a build system for Visual Studio projects) to real MSbuild (now FOSS, but an enormous shipping container of worms of its own when it comes to distribution-shippable releases, for all the same reasons & worse).