One thing I find annoying is that there's no way for me to let the company know that this behavior lost me as their customer forever unless they change their tune.
I'm fairly sure I'm the kind of person they'd market those products towards and it hurs them, but there's no wat that I'm aware of to let them know.
If there was a way, and a significant amount of people would do so, maybe the decision makers would understand it's stupid...
As others have mentionned downloading the .deb and running it will also work, but I feel nobody gave your a tldr of why you may want to follow those instructions instead, so here it is:
Those instructions configure your package manager (apt) with a new repository for this application.
The upside to that is that anytime you will look for updates, this app will also get updated.
It's a bit more work up front, but it can pay off when you have dozens of app updating as part of normal system operations.
Imagine a world where windows updates would also update all your software, that's what this is.