Yes, you are right. We have swords and manuals from the samurai period. But we don't have *all* of them. Manuals, maybe, but swords? Hardly. We have a mere dent in the number that were actually made.
One thing to remember is that there were then, as there are now, a variety of smiths and samurai. Some samurai had more money and or sponsorship than others, and could afford better weapons and/or training. Thus, some swords would survive time, others would not. Some samurai would rather destroy their own weapons than turn them over, and so we lose some there.
Kinda like the Greco-Roman sculpture: we have a LOT of sculpture from that time, but we can guess that a LOT more was made that we don't have (and never will).
When it comes to actual use, I would argue *strongly* that blade to blade blocking was not done as a regular matter. However, I would lay out good money that it happened. Either by accident, by desperation, or by "sacrifice", you can't have the number of battles/duels/skirmishes that Japan went through without a fair number of incidents where it happened. Think of it like this: A modern soldier may not *prefer* to use his rifle as a club--but prove to me that it never happened, and that it isn't resorted to. (POOR analogy, but it'll do for the moment, anyway).
Preference-wise, no, I don't think *anyone* seriously advocated doing such a thing to their blades. Yes, the sword was the soul of the samurai. They had great respect for their blades, going so far as to name them and have them blessed by priests. Yes, the blades were believed to have a soul. But remember, too, that these are the same people that viewed seppuku/hara-kiri (ritual suicide) as a means of protest in some cases. They *did* have their practical moments, where, I would argue, if they slipped, or if they poorly executed a block, or even just "did what it takes" to get out of a situation, they would have used an edge to edge block.
I am no sword-maker and no metallurgist. I can't argue any points of how swords were made, other than to say they were made to hold an edge under *most* circumstances. Edge blocking was not one of those. But I bet it happened.
Also, warriors' careers were not necessarily "over" if they lost a sword. Many could have them replaced, if broken, but at a pretty hefty price, both emotionally and financially. Remember that samurai were sponsored, and served lords--the lord may have to provide a new weapon from time to time to have his servant be efficient. That happens.
Just a historical side note: breaking swords was what caused one of the revolutions in Japanese sword design. The royal swordmaker saw too many warriors returning from war with broken weapons, or not returning at all because of weapon failure, that he sought out a better process. This led to the folded steel designs, and many of the advances in swordwork that came to represent the samurai.
Again, I am no expert, and don't want to pretend to be one. I agree wholeheartedly with those that say edge blocking is a "good" or "acceptable" idea. However, it is unrealistic to imagine it never happened, or that there weren't people that *may* have advocated it. I mean, hey.....remember again, there were samurai who advocated the killing of any samurai who had hobbies that weren't militarily or politically useful, too. (Anyone advocating edge blocking would probably be laughed at then, also, but hey.....)
My apologies for the lengthy rant......no flames intended, and all points of view accepted.
Peace--