I didn't like it because of discussions of it online. But then my Steam malfunctioned because of a Mesa update and I decided to try it anyway and form my own opinion. Turns out it works really well (for me), it's performant and I like that it installs without root password and is mildly sandboxed so installers can't put files just anywhere in my system.
It's not so much about necessity of it as it's pros vs. cons of different package managers, Flatpak vs. pacman vs rpm vs snap vs appimage and repositories (the AUR is nice for example, but also a bit like the Wild West), etc. Pick what fits your personal philosophy and enjoy.