You can differentiate between GNU/Linux users and Linux users on whether they have steam installed, and differentiate further if it is installed as a flatpak or not.
As a Linux enjoyer it's definitely true that the elitist/casual ratio is higher on Linux compared to Windows or MacOS (especially Arch manual installers), but as more and more people will adopt Linux, this ratio will probably be lower and lower.
It's not differentiating between "casual Linux users" or "real Linux users," Valve's Steam does not belong in the GNU operating system (GNU/Linux) since it forces users to install a nonfree interface and also invites users to be subject to DRM (though it is optional for developers to enable or not). The problem is not Steam's role as a content distribution manager (handling payments, delivering files), but the fact that it restricts the users freedom through their steam client (which there are no viable free software solutions to).
If a discussion of free software unnerves you, I don't care. But to label this as a conflict between "casual vs real, normie vs elite" is just unironically doing what this meme is mocking in the first place.
I think what they were specifying was the role GNU plays in that sentence. Personally I don't like calling one GNU/Linux and the other Linux, but the defining point of GNU is that it's uses only free open source software, and does not contain any non-free (as in speech, not beer) software.
Paranoid people usually will use a flatpak version of software, since that can secure the person's privacy a bit more than a non-flatpak one. (The program is isolated from the system, just like a docker container if you know what that is)