mate, you are totally right! Ive seen it hundreds of times! There is no real rule about visa runs, and actually they cant decline you( o ly if you are on a black list), but they try hard with the other rules ( 20k baht cash, flught out ticket, booking of staying). Thats how people have been sent back from the border.
I’m on medical extensions now due to my injury. You need a letter from your hospital. They should know what to write( you need farther magical treatment, can’t travel, etc).