SElinux and Apparmor are 2 of the worst and most obscure security systems I've ever seen. I have no idea what the main ideas behind either are and on what principles they work, and I've been on Linux for 25 years with all kinds of systems (embedded Pi, desktop, servers, etc...). I've never seen a proper introduction to either, the manpages are a block of lead on your head and they DO NOT work out of the box to the point where you just have to disable them if you want to keep on working. Apparmor pollutes the syslog with tons of garbage, and SElinux is the opposite, not a single message ever but things just stop working in obscure ways.