> it suddenly becomes a lot easier to just download Ubuntu than it is to install Snap for a foreign platform

That's an exaggeration. It's about as easy to install snap support for a non-Ubuntu as it is to install any other third party app on that platform. And the latter case is exactly what you're trying to achieve by trying to install a third party app on that platform in the first place, so by definition it can't be significantly harder than any alternative method.