They may be fallback methods, but snap is for sure not "great" (not a finished product as other have pointed out). As you also understood, snap is sadly not promoted as a fallback method.
This stuff is pushed with corporate power. Not adopted because great great fallback method it provides.
The compatibility is also balkanized for the start with the flatpack/snap split. Pfff, what a mess.
I'm not a fan of using it as the default though, and flatpak isn't immune to issues either, for example I use a flatpak package which regularly can't be updated for months because of some incorrect metadata if the error message can be believed.
I still think it's a good step forward for increasing compatibility especially across different Linux distributions.