That one doesn't seem unreasonable. They have a "we only support tagged releases" policy. mpv moved away from tagging releases for a bit, and their latest tagged release couldn't build on current MacOS. So they switched it to the part of their system (casks) that supports downloading and installing arbitrary binaries instead.

I think it's a fair conflict, too. For a package manager, saying "just download and compile master wherever it is right now" is rough, and I can understand them not wanting to have to look at mpv's repo and pick a good commit to pin as their "release". Offloading picking a stable release point to someone else is legitimate.