Missing .service files are a pain, yes, but unless you are running LFS, Arch, or Gentoo (Those three dont modify upstream packages), then if the distro is providing the software it should ensure that it has a relevent .service file, just as I would hope if they were using Upstart they would make sure it had an upstart file.
Systemd works on any distro that WANTS to support it. Debian and Gentoo are "incompatible" because they want to be able to swap out kernels. Thats their problem, their creating a harder environment for them to work in and placing limitations on themselves because of it. If they want to do it, they are more than welcome to, but then they shouldn't complain when they cant use something specifically because of a choice they made.
And what are you even talking about as far as working on hardware, hardware has nothing to do with it. If you have a kernel greater than 2.4.39 you can run systemd. SUSE 12 and RHEL 7 will both have kernels greater than 3.0, I think even Debian is above 3.0 at this point. So who exactly is being excluded here? People who want to run ancient kernels? I dont even think the 2.4 series is supported by upstream anymore (RHEL and SUSE may support them, but upstream mainline doesnt)