Many things happen in the Linux kernel. It doesn't matter which distro you use as long as the kernel supports your hardware. Lots of distros have taken credit for things that happen outside of what they do.
Also, just out of curiosity, did additional hardware support take away from other areas of development or was this just natural since more Linux kernel devs just use different hardware and saw direct benefit?
Distros include a unique set of packages, but after installation you can remove what you don't want and add what you do.
The single biggest factor in terms of sheer compatibility with your hardware is the Linux kernel, and every distribution has one. Some are older than others. Some projects remove things from the kernel and recompile. Others add things.
But by and large, the Linux kernel is the same from distro to distro. Some ship newer kernels, to be sure, and some ship older ones. The Linux kernel developers maintain a few different kernels at the same time, some older with security patches, some newer with the latest features and drivers.
Fedora ships new kernels all the time. If you have new hardware and have parts that are not working so great, new kernels will often solve your problems. It's not the distributions doing this, it's the kernel team.
If you have old, stable hardware that works great with an old kernel, you might want to run something like Debian or CentOS -- if you like that sort of thing.
Fedora or Arch are both great ways to get new hardware working its best, but that's because the Linux kernel developers are doing this work at the kernel level, and these distributions pick up new kernels very soon after they are released.
If distro developers contribute back to the Linux kernel -- and many do, from Ubuntu and Fedora for sure, but for others, too -- everybody benefits from those improvements when a new kernel is released for the use of all distributions that want to package it.
Before GNOME 3, Ubuntu, Debian and Fedora all used GNOME 2, and they were more alike than different. I'd say the same is true today with these three and GNOME 3, though Ubuntu skins it somewhat differently.
They really are more alike than you'd think.
I’m guessing Ubuntu is recommended because it’s most widely available or has the least amount of “under the hood” mods that make others more challenging.
Lenovo, Dell, Huawei and HP sell laptops with Linux pre-installed and supported.
IoT, we have plenty of embedded OS to chose from, with the FOSS alternatives going with MIT derived licenses.
Android since Treble, classical Linux drivers hardly count.
And anything graphics related is hardly Linux first, if ever.