As a Mac user…the article is valid.
Earlier I saw a similar article written by someone I know, published on TidBITS, a respected Mac web site:
Moving to Catalina: Keep Your 32-Bit Mac Apps Running with Parallels
Mac users may want to read that article too, for additional background and for the long comment section after the article, where the author Glenn Fleishman and the website owner Adam Engst answer user questions. If you packed a room full of Mac users, those two guys might possibly know more about the Mac than everyone else in the room combined.
I use the same virtualizer (Parallels Desktop) to run isolated Mac and Windows systems to test prerelease OSs and applications. It isn't without some complications, similar to using a virtualizer in Windows:
- Lightroom users really want more speed (like, a lot more), but software inside a virtual machine runs slower than it normally would, partly because it's competing with the host OS for CPU. Virtualization works much smoother on computers with 4 or more cores.
- Virtualization means needing enough RAM to run a second OS inside your primary one. You'll end up with much less free RAM for your other applications. If a Mac was getting by running Lightroom 6 and other applications with 8GB RAM, running a virtualizer regularly might not be satisfying unless that computer was upgraded to 16GB or more, especially if photography software is involved.
- A virtual machine takes up a lot of storage space. Adding a working Lightroom installation, including catalog and the constantly growing previews file, will probably result in a virtual machine that uses over 50GB of storage, not even including the photos being referenced. Then you have to back that up.
- I'm not sure how reliably Lightroom in a virtual machine would link to external storage, might have to try that someday.
- A virtualizer may not have access to graphics acceleration or graphics hardware such as an eGPU. The Adobe software I try in a virtual machine can't see the GPU I have, so GPU features end up disabled. Though Lightroom 6 and earlier didn't benefit that much from a GPU anyway.
- Most virtualizers are paid software. The Pro version of Parallels Desktop is a subscription, but the Home/Student perpetual license version works fine for this and you can delay buying the next upgrade until you really need it. I suppose free VirtualBox would work, but I don't know how well or how easily.
So think hard about whether this is a road worth going down. It would be more acceptable for those who only use Lightroom occasionally, possibly impractical for daily Lightroom users who simply don't want a subscription.
If someone has enough storage for a virtual machine, it might be a better idea to instead set aside the same amount of storage space, assign it to a new APFS volume (like a partition, but more flexible), and install macOS 10.14 or earlier on that volume to run 32-bit applications. Reboot into the 10.14 volume and Lightroom will run at full speed with full access to all resources. A virtualizer may be better if the many hassles are worth being able to run the older applications in a macOS 10.14 virtual machine while the Mac is actually booted into 10.15.
Stop struggling with Lightroom! There's no need to spend hours hunting for the answers to your Lightroom Classic questions. All the information you need is in 
