How much of the distinction in those cases is based on ease of conversion to full-auto? That puts me far outside of my knowledge space.
I'm not a gunsmith so I can only go based on hearsay, but I don't see any particular correlation with ease of conversion on the lists. For the most part, the items on the prohibited list are those firearms which have been "widely recognized" (for some definition of "widely") as military firearms at the time that list was originally drafted. Hence it has e.g. AK, FAL, G3 and such, but not Vz 58. It also seems to be specifically excluding firearms of American origin, such as M14 and Garand (for Garand, the law even allows it to have a the original 8-round magazine). It seems that updates have been rather ad hoc, and my understanding is that those updates (as opposed to the original list) have been driven largely by full auto convertibility, as shown in the past scandals with acceptance followed by recall of QBZ 95 and SIG SG55x. It largely ignores new firearms that have been designed since the list was originally drawn up - XCR, ACR, Tavor, most Kel-Tec offerings etc are all notably missing, and the corresponding manufacturers have seized the opportunity to grab the market in the absence of competition.
Regarding the "moot" between semi-auto hunting & military, I largely agree as well, though I see the five round (or some other small number with slowish reload) restriction as critical to the point of the civilian safety
The effective limit in Canada is more than 5 right now due to that silliness with the distinction of "pistol" and "rifle" magazines, and the fact that they're restricted based solely on that distinction, rather than actual use in a firearm. In particular, Rock River Arms manufactures an AR magazine for their LAR-15 "pistol" (which is a pistol according to the law because it lacks a stock). That one is therefore 10-round. But it is perfectly legal according to the law to load all 10 rounds and then stick it into any rifle that will accept it - and because it is basically just an AR mag with "for LAR-15 pistol" stamped on it, it will go into any AR (restricted), as well as XCR, Tavor, or SU-16 (all unrestricted).
For another example, consider pistol-caliber carbines, such as Beretta CX4 Storm, or Kel-Tec Sub-2000. Those are usually designed to accept some existing popular handgun magazine - Beretta 92 for Storm, Glock or Beretta for Sub-2000 etc. Again, because the mags are considered as designed for use in a handgun, it is perfectly legal to obtain a 10-round one and then use it in a carbine.
But wait, it gets better. The law furthermore restricts the amount of rounds in the specific caliber for which the magazine was designed. But in many cases, new calibers designed in the past 30 years were intentionally made to reuse existing magazines - especially AR ones. In that case, the capacity of the magazine actually depends on which rounds you load into it, and it can be used with weapons of different calibers without any modifications (other than swapping the rounds). The most extreme case in point is .50 Beowulf - it uses the standard AR-15 magazines, but the round itself is ~1.5x thicker. Consequently, a Beowulf magazine that holds 5 rounds - and therefore legal, on the assumption that it would be used with a rifle chambered in Beowulf - also happens to double as a 15-round 5.56 magazine that works in any AR or compatible rifle (i.e. the same list as above). So long as the mag itself is stamped ".50 Beowulf", it is considered designed for that round, and hence legal to use for any purpose, including loading 15 rounds of 5.56 in it and using it with an AR.
So, in effect, someone who is reasonably well versed in gun laws in Canada today can have a military-like semi-automatic rifle chambered in 5.56, with 15-round detachable magazines, and all this is classified as "unrestricted" - meaning it only requires a PAL, and it can be freely transported subject only to basic safety restrictions (i.e. requires a secure enclosure, a trigger lock, or a detached bolt; with an AR, reinserting a detached bolt is a matter of 2-3 seconds), so you can legally drive around with it in the trunk of your car.
For comparison, this is actually roughly equal to the restrictions currently in place in Colorado, and more liberal than either New York or California.
As to how much it actually helps... I don't think it does, to be honest. On one hand, reloading a semi-auto rifle is a very fast thing, especially if it uses drop-free mags (like AR), and has a bolt hold open and bolt release (again, like AR). Search for "AR speed reload" on YouTube and watch a couple of videos to get an idea. It's even faster with pistol-caliber carbines that have magazine in the pistol grip, Uzi-style, because there the movement is a natural "hand finds hand".
On the other hand, frankly, events involving those rifles are extremely rare. It's kinda like airplane crashes - they get a lot of publicity in the press because of that rarity, and because seemingly many people die at once at the same time from the same cause, and of course there's usually a drama involved ("why did poor Tommy decide that he wants to shoot all his friends? he was such a nice boy!" etc), all of which sells. But if you look at raw numbers, the chances of being shot by an "assault weapon", with or without a hi-cap magazine, are somewhere in the ballpark of being struck by lightning on the porch of your house. Most people killed by guns, including in US, are shot by handguns (and usually it's actually .22 LR handguns), and the shooter usually makes just a single shot, sometimes 2-3. So I don't see mag size restrictions as been "critical to the point of civilian safety" at all. Background checks make a far bigger difference.