The non-techie folks are fun but they mostly just complain about their iPhones changing overnight and a bad Windows driver update. It's nice to just sorta be done with that rat race and focus on free software, if it's all the same to you.
That doesn't mean anything anymore. Such omenous warnings pop up everywhere, even when installing legitimate drivers and applications or updating your software, that at one point you desanitize yourself and just click Yes, Next and Accept to everything to finish the installation and start pwning some n00bs in your vidja games.
Blaming the user here is stupid, especially since Linus was following the instructions he found online, which is exactly what most users would do, even if one of the steps throws an omenous warning.
As a clueless user coming from Windows you don't expect that a Steam installation should lead to the uninstalling of your desktop environment and display server, since on Windows these are part of the core OS and no amount of fuckery can remove them. This is a massive barrier to entry for new users on Linux.
That's why Valve threw in the towel on convincing people to install Linux on their PCs and instead sold them a PC based console with Linux preinstalled and already configured to run games. Linux on the mainstream home PC is a dream that even Linus Torvalds said won't happen.
I'll happily blame Linus and his vidya-addled brain if that's what you want to blame it on. I suppose that's why kids ate the Tide pods, after all.
Case in point, Microsoft Excel throws a big scary warning every time you open a file and enable editing mode. For completely basic usage, Microsoft throws in the towel and claims that anything bad happens is on you. Why should anyone expect users to take these messages seriously?
Get out of your techie bubble and go see how actual non-GNU humans use computers to get a sense of how poor some SW can be at communicating information to clueless users and how little interest clueless users have to learn the nitty gritty things about their machines. They just want to play games or whatever.