I agree. I learn Muay-Thai (Thai boxing), and this is incredibly useful, mainly because I have to (try to) switch from my usual "thinking for hours/days/months to a problem" mode into "flowing, neglecting analysis/systemics/... and letting whatever is left take control and act/react RIGHT NOW".
This is really a problem in the professional world, and at a lesser extent in some high-end amateur setups, mainly when some competitors want to become pros or if there is some animosity between gyms/people.
They cut weight, have good technique and power, and the stakes sometimes are very high. This is dangerous.
Cutting weight reduces the amount of water in the body => the brain bounces on the skull at a greater speed => more kinetic energy => major risk (hemorrhage...).
Many sports are much more dangerous than commonly thought. Each and every friend who practiced judo or BJJ developed serious joints problems, or even major hips-related ordeals. Comparing football and MMA leads to surprising observations: https://bleacherreport.com/articles/2830774-football-vs-mma-...
My take: do not compete (and do not aim at becoming a professional!), avoid any gym where hard sparring is mandatory, or where the trainers don't closely monitor the sparring sessions or don't immediately break anything getting out-of-hands. There is some residual risk, but IMHO probably no higher than walking down the streets, and the gains are worth it.
This is a really fascinating perspective, and contains info that I hadn't come across previously. Thanks for sharing; I'm excited to read a bit more about these points.