Well, after 15 years of fighting as a heavy in the SCA, quite successfully, and about the same time in HEMA studies, I feel qualified to say that this is a very vague, and apples to oranges discussion.
I really don't want to get into the origins of SCA blow conventions, which claims a good blow is meant to penetrate
mail armour, although that idea was invented 44 years ago with no real data behind it - we now know that armoured knights in riveted mail died to successions of blows, not to a single, mail-shearing blow. So, the convention stands, but really means a hard, solid blow. What is "full power"? Certainly what constitutes a "good blow" in the SCA varies from kingdom to kingdom; to put it in SCA parlance, a basic good blow in Meridies (the Southern US) certainly isn't a good blow in Atlantia (DC area) or An TIr (Northwest). And what is a "good blow" might be the hardest one person can hit and not even close to what another can do.
But in truth, the blows are hard, but not so hard as to be a danger to someone wearing SCA minimum armour. Which is only a 16 gauge steel helmet, hard elbows, knees, kidney protection, a gorget and kidney protection. Hockey gloves are the standard for hand protection. Yes, most people wear more than that, but that remains the 'standard' for safety gear. It is still a minority for many, many people to wear anything close to the mail hauberk over padding and helm (or helmet with mail drape) that the SCA "standard" is meant to represent.
Conversely, WMA "unarmoured" combat assumes that the opponent is wearing street clothes or a gambeson, and no more, so a solid cut or thrust will do the trick. While some groups will allow a lighter blow that I would, for most places this means that the blow needs to be solid - no flicks, draw cuts, etc. Do people hit as hard as they can? No. But there is no purpose in doing so, there is no assumed armour to counter. Do they hit *hard*? Often, yes.
I certainly agree that a fencing mask would be caved in by such a basic SCA flat-snap with a rattan club. But I also don't think it suitable for a longsword match, either. Which is why, my own group, and many others in the US, wear a gambeson (or padded, leather fencing master's jacket), steel gauntlets, hard elbow protection, a gorget and a helmet, specifically designed for the activity, such as those made by Windrose Armoury:
http://www.windrosearmoury.com/zc/index.php?m...cts_id=641
IE: we're wearing about the same gear as SCA minimum standards, and in some case a bit more. Which is hardly armoured combat, but then that was my point - neither of these activities actually require a fully armoured man. :)
I will also note that while a rattan baton hits with less authority in most places, the wider surface area actually means that it strikes harder in many ways to the head - many blows that will cause a thin steel blade to glance off a
bascinet or reinforced coaches mask "stick" with a rattan baton and transmit force differently into the target.
Honestly, one thing the SCA does is hit hard, but what precisely that means vis a vis unarmoured swordsmanship, or what that means outside of your experience is really moot. Your assertion that "NO HEMA group does this" is a lot like someone saying that no SCA event does real armoured combat, since no matter what a combatant wears, the combat convention remains the same - one solid blow thwarts any armour worn, giving a strange advantage in what is ostensibly "armoured combat" to people who wear close to SCA minimum, while penalizing a man in full plate kit. That *is* true on the surface, but it is also true that tere are SCA specialty tournaments, and have been since I was fighting in them in the 90s, that allow for armour as worn, and other events, like the Pennsic Battle of the Thirty, that have allowed half-swording, light grapples, knockdowns, etc.
Martin was quite right - this is apples to oranges, especially as there is no universal HEMA standard, so unless you are really involved from the inside and interacting with a wide variety of groups and practitioners, sweeping assertions are inappropriate.
Having done both activities, you will find varying degrees of force and aggressiveness in both, and wildly varying degrees of skill in both. But good fighters tend to be good fighters, be they HEMA, SCA, kendo or modern fencers.