Those techniques are not useless at all. In fact they can be killler tools to have in one's toolbox. However, you've got to know when to use them and when to not use them. Trying to eye gouge someone when you are mounted on them is hugely different than trying to eye gouge someone when the postitions are reversed. The first is highly effective. The second is a big mistake.
I could show you some devastating toe breaks. Unfortunately, you wouldn't be able to use them unless you were skilled at getting into position and isolating the foot.
Some of the Filipino biting "systems" can be very effective. These techniques are much more effective for someone who understads the positioning that is used in MMA fighting.
They are most effective for the more effective fighter.
But the MMA fighter is usually more adept at getting to a position to deliver them.MMA are just as susceptible to a headbutt as a tma'er.
The point that the TMA artists make is that these things would even the playing field if they were allowed... they would not, however, make things more even. They would just tilt them more in favor of the MMA fighters.Some skill sets are outside of those limitations while that is the world that MMAists thrive in, the good ones at least.