I am sure there is no scientific backing to Broz' claims. But I find the reasoning somewhat plausible. The technical execution becoming more staple when doing a movement A LOT certainly makes sense as well.
But no matter the mechanism, it is certainly true that via very high frequency the training intensity HAS to be lower compared to what it could be when training in a rested state.
If we would assume for a second that higher intensity increases the risk for injury and higher volume makes for more opportunities for an incident to happen, albeit not increasing risk via an additional mechanism, then high frequency training would have you train at safer weights while still providing a very potent training stress. This look at things puts the Bulgarian method, that gets critiqued in the article, in somewhat of a different light. It also leads to the question what the training percentages in the article actually mean: What is 80% of 1rm? 1rm of that particular day? Training 1rm? Competition 1rm? And did every writer always mean the same thing with those?
Good point, I would say that the Bulgarian(ish) approach could actually be even less risky, due to the reasons you listed, and also the very frequent "practice".
Its kind of funny when people react to this type of training as "harder" and "insane" etc. Imo, its actually easier, and a lot less draining than many other set ups. The use of the word "max" is partially to blame. Ive mentioned it before, but if you look at most of the a.b.g. videos, theyre not showing a grinding, screaming, true MAX, MOST of the time. Its more of a routine, heavyish lift, that looks like it could be repeated if need be.
There is a coach named David Woodhouse, who has recently pushed his program nicknamed the "syyyystem", that entails lifting only 2 x a week, and VERY low volume on those days. It entails front squatting to a MAX, along with doing the classic lifts in a similar fashion. This would entail more of a "real" max, and here is an example of one of his guys on a "max" front squat in one of their sessions.
http://www.youtube.com/watch?v=DgLpAzGfH0IABG guys, lifting daily, and here is what you tend to see most often as one of their "max" lifts, daily.
http://www.youtube.com/watch?v=3-SEt13Wyhc It would be more accurate, to say woodhouse has his guys going for a personal best each session, and the a.b.g. guys are going to a daily "heavy single based on autoregulation". When training that frequently, the autoregulation will happen to some degree regardless of desire or will power to lift past a certain point.
I was reading earlier an interesting programming thread on Glenns forum where some of this is discussed and found some of the experiences to follow along with the same line of reasoning.
http://www.pendlayforum.com/showthread.php?t=3168&page=5