The fallacy part of the slippery slope fallacy isn't that it can't happen, it's just assuming that it applies to everything because it applied to one thing.

Everything about society is arbitrarily deciding who can and cannot do shit. You can't practice medicine without a license. You can't get that mortgage without a good credit score. You can't drink if you're not old enough.

It never progressed to the point where nobody could practice medicine or get a mortgage. At one point they actually tried to say nobody could drink but that didn't last long before everyone soundly told them to fuck off. So there's nothing inevitable about the slippery slope in every case, some things just naturally stop at a point the majority of society agrees is reasonable. It depends on the context and the process.

In the case of restrictions, that's a zero sum game, if you're saying there's a slippery slope of increasing restrictions then you're precluding the possibility of a slippery slope of removing restrictions (E.G. gay marriage -> transgender kids -> legal pedophilia) Unless you're advocating the very specific case that the the status quo is incredibly unstable and balanced on the knife edge of snowballing in the direction of whatever change comes along first.

A slippery slope of restrictions affecting an ever increasing number of people is not a natural situation, each step is harder than the last as an ever larger number of people are directly affected and will naturally resist it. It takes a considerable amount of social engineering and then some muscle to silence the dissenters who resist the conditioning to keep that process going beyond the point where it affects a majority of people.

But a slippery slope of removing restrictions on ever smaller groups can happen naturally in some circumstances. People obviously won't resist fewer restrictions on themselves and people don't naturally resist lifting restrictions on others unless they believe those others will do harm without restriction. If the biggest group of a collection of groups considered to be equivalent and potentially harmful manages to get the restrictions lifted and proves not to be harmful, then it can trigger a cascade where people no longer believe that the smaller groups will be harmful without restriction if the bigger group proved to be safe. Problems can happen there if society at large mistakenly lumps inequivalent groups together, such as believing gay is the same as transgender is the same as pedophile.

lol- yeah this moral free for all has gone great- more of that- I'm sure we'll turn the corner-

That doesn't change the fact that this is a really shit, low effort comic page

You're not completely wrong, but what you're missing is that the whole thing is a laughable strawman. Yes, "our side" jokes about not allowing unfit people to breed, and for 99% of people, it stops at being a joke, forever.

What I, as an actual conservative russian nazi troll white supremacist, would like, is to end welfare and affirmative action and related programs, including "diversity hiring" by private companies, because welfare only incentivizes unfit people to have kids and then fuck them up by failing as parents, and AA etc. only ensures the product of these fuckups can gain power and fuck over normal people like the spiteful mutants they are, despite being unfit to have any power over anyone but themselves. Take away the perverse incentive to have kids and raise them wrong, and it works just as well as banning certain people from procreating, except nobody needs to be banned from anything. Take away the way to gain power over others through being a fuckup, and the few kids who were failed by their parents will stop endangering everyone with actual merit.