Firefox is larger on macOS because it contains 2 archs (x86_64 and arm64), not because it bundles of full runtime -- also the compression algo of dmg files is typically quite bad (zlib or bzip2), which is not helping.
In fact, this reinforces it. OSX believes file size matters so little they’re willing to double file size simply so users don’t have to pick x64 or x86 when downloading the app (and if they’re using the App Store the App Store could do it for them, but even that Apple thinks is too much complexity).
Aaaand folks who live in the Apple universe have been accustomed to accept that they are holding it wrong, and that there's someone whose job is to figure out what's the official best way to do things. If it involves downloading 130 megs it's 130 megs. No problem. The UX and end result is worth it for them.
Having said that, I never bothered installing it on my current laptop which sort of reinforces the point others are making about being less concerned with application size.