The altertnative approach (and maybe more realistic from what I could see from the PR they opened) would be to compile a list of all those variables and build a file one could source to disable all known telemetry (it could include that variable and allow things to migrate progressively)
But buy in is worth it. Consider the related issue of every damn app not respecting a users home directory and polluting it with every file. But that's a problem the XDG Base Directory Specification was designed to solve. And things are better now, though you often have to explicitly set the XDG variables to get some applications to respect the standard. But just having a standard pulls people and organizations in to follow it.
