Why do people believe stories like this? Don't get me wrong - I think he really believes what he wrote, but an OS install doesn't cause that kind of damage or prevent one from upgrading their machine. The issues lie with the person installing, not the software and from what I've read here over the years regarding various beta releases, some people should never install them at all.
During the course of this beta I've read some of the wildest stories imaginable - just like you read every single Summer beta cycle. The first and second betas had issues with the 2018/19 hardware, that was about it. I have a 13" 2017 MBP, no taskbar. My installs went without a hitch. I had issues with overheating and fan speeds, iCloud was a mess (still is, was, and probably always will be because Consumer-grade cloud services are crap by their very nature) and I'd even go so far as to say that the Mojave beta cycle was probably a lot cleaner.
It's a BETA - what do people not understand about this idea? Catalina is shaping up to be a great iteration of MacOS - what do people want? I know exactly what's going to happen. By about 15.5 or 6 Catalina will be humming right along and I'll be stupid enough to participate in the next beta cycle knowing exactly what I'm getting myself into...