Some of those comments are true.
For those that incorporate sparring and scenario based drills, Training for "self-defense" includes NON-physical skills like visual awareness, de-escalation strategies, use of improvised weapons, etc.
I know of MMA gyms that teach these other skillsets and also say they teach "self-defense".
I knew a girl who I would NOT have put money on to protect herself. She was on the shorter side and overweight. She was in college and went to one of the buildings to work on a project after hours. She was leaving when she was accosted by a man who was about a foot taller than her. He tried to drag her into one of the rooms and she fought back. He tried striking her (giving her a big black eye in the process). While they were fighting she was able to strike him in the groin and bought enough time for her to run away.
Was she successful at "self-defense"? Yes
Would she EVER have been successful at ANY type of combat sport? No
"God gave you a brain, and it annoys Him greatly when you choose not to use it."