That is a bunch of nonsense. First of all, in any open water class it is usually emphasized that all of the basic skills taught should be practiced for mastery after you get your certification. So the idea a diver does a skill once and then should forget about it is wrong.
Second, since entanglement in either cave line in a cave or fishing line and nets on a wreck, not to mention the other entanglement and passage issues of that type of diving is greater than what the average warm water tourist diver being led by a DM would find, I'd be shocked to learn those skills are not emphasized and practiced in cave and wreck courses. Especially considering the more complex gear configurations required for technical diving.
Finally, you've just read quite a few examples where fellow board members have had to remove their rig. Many with decades of diving experience and then you essentially state they are ****** divers.
Let me ask you something, since your situational awareness is far superior. How are you able to see fluorocarbon under water when no one else can?
Most entanglements are elementary, unless you've never practiced the skill.
Here's an example of an untrained diver dying because he was separated from his group, got tangled and then panicked. He died at 25 fsw with 2200 psi still left in his tank. He had plenty of time. Sad.
Divers Alert Network, Untrained Diver Dies Entangled in Kelp