The time thing is a bit of an issue, and why I am so glad I can point to Miyagi and say “it’s time to update somethings” because that’s exactly what he advocated.
Either some MT/KB style training needs to be brought into karate to get that quick boost into some sort of practical skills, or karateka need to spend 6-12 months in something like MT/KB.
the 50s-60s saw a lot of evolution, very much inline with miyagi’s quote about learning from other styles. That’s how KB came to be, that’s how shotokan got its high kicks, but then around the 70s or 80s people no longer wanted to change anything or make anything new.
so yeah instead of adapting a combat sport to self defense I think we NEED to adapt a self defense style to combat sports
But why do we need to adapt a self defense style to a combat sport if not everyone is interested in combat sports? Those who are interested in combat sports can pressure test their self defense style under those rules but a lot of people are interested only in practicing Karate mainly for self defense which is it's intended purpose.
To add some input to the original point you made this thread for but I trained with a guy who competed in a local men's Shotokan point fighting tournament in the United States about 11 years ago and he said they were landing full power strikes on one another similar to the karate kid tournaments you mentioned. Figured I'd add that info for whatever it's worth since I vividly remember him saying that.