Re: Irrational fear of upgrades?
Well, I mean, it's kind of a spectrum. Or a set of overlapping spectrums.
It's true we couldn't test a room full of hardware on our current release schedule. But then we also probably couldn't test it if we released every two years, either. There's a *lot* of hardware. We have like a dozen paid QA folks and maybe the equivalent in volunteer person-hours. We'd probably need till the heat death of the universe to test all combinations of hardware.
Ditto for "software combinations". There are thousands of SRPMs that make up Fedora. Just the possible combinations of those packages are effectively infinite - never mind the confounding factors of configuration and what you actually do with them.
If you spend much time thinking about this, like QA people do, the conclusion you tend to come to is that it's a miracle that anything works as well as it does. And there's kind of less difference than you might think between a six month release cycle and a two year one, in terms of what it's possible to test as a percentage of all the things that possibly *could* be tested: the answer is "infinitesimally small" either way.
Realistically, the only way you can really 'comprehensively' test software is to have that piece of software be very small and be required to do only a small and very clearly defined set of operations. This is how you do things when you *really really really need* the software to be reliable. Like when it's running a plane or a dam or a spacecraft, for instance. But you can't do this for general purpose operating systems, because they're...well...general purpose.
So yeah, stuff breaks. Fedora sure does. And so does RHEL, and macOS, and Windows, and Ubuntu, and SUSE. They *all* break. They're all in a perpetual state of some stuff being broken. It's not practically possible to achieve any other state, really.
I don't honestly think any given Fedora release would be substantially more "stable", in the sense you mean, if we went to a one year or two year release cycle. We don't run out of time to test the stuff we test, these days, and we haven't for some time. What would make Fedora more "stable" would be to slow down the pace of changing bits of it and adopting new things, but then it wouldn't be Fedora any more. And indeed if that's not what you want, you shouldn't run it; there are, as you note, other choices.