I know its been around forever, especially in those days when it was TRULY win at all costs and NHB. These are completely different times in the sport. In royce' case, he was generally very undersized and trained that method regularly in the day to day, as it was, and still is an effective method of self defense and a way for the smaller guy to get rhe bigger guy down to the ground, no matter the outcome. This is a huge part of bjj and He grew up training to protect himself by any means necessary which crossed over perfectly to MMA at that time.
It hasn't caused that many injuries because it is not commonly used. You have to ask, why is that? Fighters know its legal, know its effective, yet still choose to not generally use it. As stated, many fighters ober the years say its cheap and dirty and can easily lead to surgery and the end of a career / lifestyle. Rampage said Jones fucked his knees with it, Reyes or Santos, can't remember, said Jones fucked his knees with it. Interesting how one of the dirtiest fighters if all time is the one apparently wrecking knees with it. Again, the more its used, the more fighters overall will use it since it get more adopted. As that happens you will see way more career changing injuries which will eventually lead to a ban anyways. Why wait for a bunch of guys to get wrecked first ? The ones calling for bans aren't doing so cause they don't like kicks in general, they are doing so cause they are very aware of the outcome and most of them don't want to see that happen to their friends , co workers, or themselves. There aren't that many fighters out there, comparatively, who truly want to fuck people up beyond repair. They are all in the same business and they all provide for themselves and their families in the same way.
As far as the subs you mentioned, fighters usually have a chance to tap before major damage occurs, unless the other fighter is dirty and doesn't let it go. Orbital bones normally heal as well. I'm not saying other attacks don't lead to injury , of course they do, some very severe, they just don't have the same likelihood of career and life changing injury, proportionately to the amount of times they are used.