I'd happily never customize a theme again if there were any other easy way to actually pick the background and foreground colors on all of my apps. I like having white text on a black background, not a "dark" gray background and white text (and certainly not some off-white background with some dark but not fully black text, which I find even worse than just a typical black text on white background theme). I'm well aware of the fact that it probably does nothing in terms of actually affecting the battery life of my devices, and that dark gray is considered "better" from design perspective, but I don't care, because I happen to like the way the color scheme I describe looks, and I don't see why it should matter whether it does to anyone else if it's just going to be on a device that I'm the only one who ever uses. For whatever reason, this is next to impossible to do without rolling my own GTK theme (not even just using one that someone else had made, because I literally couldn't find one that just changed the background to black without having a bunch of other opinionated decisions on icons and padding and stuff), so that's what I do. I'm grateful that this is even possible though, because apps that aren't GTK (or Qt, which is also possible to theme) often don't provide any ability to theme whatsoever. With the exception of coding editors, I'm not sure I've ever found an Electron app that actually lets me pick a fully black background color, so despite not being particularly dogmatic in my opposition to them, I always try to run stuff like Slack and Discord in the browser so I can theme them with custom CSS. (I'm vaguely aware that this might be possible to do with the electron apps as well by running in some sort of developer mode, but I can't be bothered to spend a bunch of time trying to replicate what I already have working in the browser for their sites).

Expressing their argument as "don't use custom themes" just makes it less convincing when there aren't really any other easy ways to get the flexibility from them that doesn't cause any of the issues they cite. It would be like finding out that a friend or relative uses the same password for every site, and then trying to get to them to install a package manager by uninstalling Windows and switching to Linux at the same time. Mixing together subjective personal preferences with objective technical advice just dilutes the latter to the point where it's impossible to find it compelling.

This has to be an April fool's kind of website. I can't believe it.

This is peak nonsense