There are issues that simply cannot be resolved without switching away from Windows. For example inefficient drivers, old hardware, telemetry and privacy issues in general. I've several times seen how Linux can bring new life to old computers, make the PC cooler, and the fans spin less or not at all under low workloads.
The primary instances where wouldn't recommend Linux is when the person is:
Using DRM-heavy games that (on purpose) refuse to run on Wine/Proton.
Using Windows-only proprietary software or drivers.
Isn't ready to learn a new system (e.g. an older or disabled person).
If these issues don't exist, I think Linux can bring benefit to a Windows user. If they are not ready to do a complete switch, they can dual-boot and try it out.
Tbh I would probably only bother to use a Linux machine for a media server really, Windows isn't going anywhere anytime soon, computer games, widespread office and engineering support, general purpose software support and the fact that everyone uses it is the big three reasons why it's still around, just look at how well Android has managed to stick around.
I think the only way for Linux to get ahead would be to offer easy potential alternatives to all these things, even then they're only just competing
It's like one extra step (install Lutris) compared to Windows. Using Linux doesn't have to be some archaic mystery and the proliferation of the steam deck is doing wonders at improving the ease of use of all this stuff.
Personally, I don't really mess with battlenet games at all, but my understanding is that you can open Lutris and install battlenet pretty easily. Then just like on Windows, you install Diablo via their installer, and for most people, it works out of the box.
You can also download battlenet directly and add it as a non steam game to steam and then run it using their Proton compatibility option. This also works on the steam deck.
Look, I'll be the first one to say that gaming on Linux is not as easy as it can be on Windows. But it is definitely not a bad experience, and hard core gaming is not the majority use case for computers. We have billions of PC users in the world. Under 3 million play Diablo 4. That is a fraction of a fraction of a percent.