Oh, nothing wrong with Fedora specifically. I also recommend Fedora KDE to people like this.

But, imagine you saw someone use a project somewhere online you want to try and it's not popular enough to be in the repos. Now you have to git clone --depth 1 --recursive blah blah blah, source ~/cflags.sh, mkdir build, cd build, cmake .., make -j4...

Doesn't sound difficult. But over time, your home directory becomes FULL of random ass git repositories. AND your /usr/local/bin is full of outdated stuff, sometimes overwriting updated stuff in /usr/bin. Having the AUR reduces that significantly.