So I'm a licensed RPAL holder (and I got handguns before the 2022 freeze on handgun registration, which is bullshit and I pray it gets repealed, even if it takes several more years). Canadian firearms law right now has been hyperfocused on banning as many different models of firearms as possible. It actually wouldn't be feasible to ban semi-automatic rifles and shotguns, but they're doing it in such a way that they're basically looking at every model made or being made and banning it by name. This is how we get lists of 15,000 individual rifle models and several thousand AR-15 variants (the AR-15 is basically banned in Canada right now. But they have barely collected any one of the rifles that have been prohibited).
In historic terms, gun laws were all about controlling 'undesirable' groups in society. That means minorities, First Nations, and any leftist/labor union. Despite what the Liberals would like to say, I seriously doubt Polytechnique was the real catalyst behind the current system passed in 1995, and was probably due to the Oka Crisis were First Nations people with AK-47s (which was likely made prob in 1995 very specifically because it was the main rifle they had in their arsenal). Polytechnique happening shortly before in 1989 was a great boon to that movement. BTW, despite it being decades ago it is STILL cited as the number one justification why continued restricted are necessary. I would go on about how much more dangerous it is to have ignored incel and incel culture (the Polytechnique shooter was a proto-incel), but that is beyond the scope of it.
Before the Oka Crisis, there was the October Crisis in the 1970s, which was the event that spurred the first law regarding the acquisition of long-guns. Before 1977, you could walk into any gun store in Canada and buy any rifle or shotgun you wanted with no licence whatsoever. And yes, machine guns were legal until then. We like to act like Canada somehow was always much stricter than the US when historically this wasn't the case. Silencers weren't illegal or controlled in any way until 1969, and there are mail order catalogs where you could buy fully-automatic WW2 surplus submachine guns through the mail. I need to mention that Machine guns were never available via mail order in the US, despite what some might claim. I should also mention that the 1977 laws only controlled the purchase of long-guns, not their ownership. So if you got a FAC (Firearms Acquisition Certificate) in 1980 and bought a dozen AR-15 or Mini-14 type rifles and shotguns, and your FAC expired in 1985, you could still legally possess and use your long-guns. Ammunition was entirely uncontrolled at the time, too. No permit was required to purchase ammunition and ammunition was available at any Canadian tire and many hardware stores.
Going back further, prior to the 70s the main gun laws were based on the 1892 and 1913 criminal codes that prohibited concealed carry of handguns without a permit (1892) and transporting handguns without a permit. The 1913 law was passed due to fear of immigrants and labor unionists arming themselves (which was common at the time) and police would literally just wait outside some gun stores to arrest people who came out with legally purchased guns if they thought they were part of a union. After WW1 they tried (and failed) to pass licensing laws for long-guns, but that law failed hard due to its unpopularity by just about everyone in the country. After WW1 the threat of socialist and communist uprisings was at an all-time high. It was the First Red Scare and in many ways it was worse than the second Red Scare of the 1950s. The origin of most modern gun laws in Europe (and commonwealth nations) originated in that time. This may have been mostly an anti-handgun thing and didn't apply to long guns, but I am not entirely sure. Handguns were still available without permit until 1934 when handgun registration was required. They had to issue a registration certificate for the handgun you wanted to get. In 2022 as I mentioned in the beginning, they basically stopped issuing those certificates, so all older registrations are still valid. Getting new handguns will be a problem.
Long story short, it was always, always, always about controlling the population at large and a fear of an armed populace wanting change. They can ignore tons of unarmed protesters, but not if even a small amount of them are armed (I can cite more examples like the Black Panthers showing up armed basically resulted in California passing highly restrictive laws to combat them, even though the Black Panthers didn't kill anyone). The modern fear of mass shooters got started in the 1980s and 90s. There were always multiple victim public shootings and Canada has had its fair share, but I do not believe that that was the main reason. Canada had multiple shootings leading up to the 2020 OIC ban, but I am quite confident that neither the Quebec Mosque shooting nor the Nova Scotia shooting (which was done with smuggled firearms from the US) had much to do with it. COVID-19 ushered in the era of increasing authoritarian control in most countries and tech giants going public with their disdain of democracy is making it so. More gun laws is just part of a greater package.
If you're looking to have a pro-protester/leftist militia in Canada, you're going to find yourself between a rock and a hard place. The entire system (and I don't just mean the gun laws) are built specifically around to prevent anything like that from happening. The last time anything like that was remotely possible would have been the 1980s to early 90s when gun laws and surveillance weren't as advanced as today. Meanwhile the RCMP has been trying to get 'lawful access' to people's internet usage without warrants since 2001 (I think pre-9/11 2001) and the latest bill C-22 is their latest attempt. This means organising anything like that will be extremely difficult without the RCMP and local police going hard on your ass.