> Not all 3rd party developers seem to have gotten that memo
This frustrates me to no end on macOS. Not only do you see crappy installers like you said, but a ton of applications now aren't even self contained in ~/Applications like they should be.
Apps routinely shit all over ~/Library when they don't need to, and don't clean up after themselves so just deleting the bundle, while technically 'uninstalls' it, you still have stuff left over, and it can eat up disk space fast. Same crap that Windows installers do, where they'll gladly spread the app all over your file system and registry but the uninstaller doesn't actually keep track of what went where so it'll routinely miss stuff. At least Windows as a built-in disk clean up tool that can recognize some of this for you, macOS will just happily let apps abuse your file system until you have to go digging.
Package managers on Linux solved this problem many, many years ago and yet we've all collectively decided to just jump on the curl | bash train and toss the solution to the curb because...reasons?