This too is total bullshit.
You cannot train "without rules" because rules keep your head and body intact so that you CAN TRAIN TOMORROW too.
They also ensure that your training partner CAN TRAIN TOMORROW too.
People who say "the problem is, boxing has rules" are not fighters, and have no idea what they are talking about.
I'd put a pro boxer up against "Mr. Streetfighter" any day, with or without rules, and expect the pro to not only win, but to BEAT THE LIVING SHIT out of mr. idiot.
The rules are in place to keep you relatively safe.
After training with the rules, in a full contact environment, it is very little work to adjust your tactics for "dirty fighting" if a problem should occur on the street.
Again, a boxer who is "fighting dirty" on the street is far, far, far scarier than Mr. Streetfighter is when he is "fighting dirty" on the street.
The two simply do not compare.
But I highly recommend you take up a wrestling art as a primary foundation, and a GOOD striking art (boxing/thai boxing) as a secondary solution.
And WORK THE CLINCH.