Putting security in scare quotes doesn’t make the actual risk go away. This is a blatant anti ad block move, but you aren’t making reasonable arguments either.
One can find reasonable use cases for every security measure that takes away freedom. That doesn't mean that all such decisions are balanced, and I'm advocating that the user be the one deciding their level of security, knowingly. That's the most important part being taken away, actually. Until there's palpable resistance (or even doubt or endless debate), those taking things away have no reason to stop.
As to your security argument: If you've never seen the past user's desktops filled with browser hijacking and ad / virus ware, then I'm happy for you, but ignoring serious security concerns isn't a valid approach to managing an end user product regardless of the nebulous slippery slope freedoms argument you're attempting to make.
This is not an advocation to ban all adblockers, but you are advocating for basically a free for all, and we've seen how that works. It doesn't and this entire discussion is a waste of time.
But it is a slippery slope and we're already sliding down, even if we don't want to. It's hard to make users switch to something else. I know it, I assume you know it, probably everyone on HN knows it. But, and this is key, Google knows it. People are resistant to change, especially if it means altering their workflow. Where said workflow depends on a monopolistic product that's key to unlocking even more ad revenue, do not think that those with incentive won't hesitate to push for more restrictions while claiming they have our own best interest in mind.
No one brought it up now, but there have been cases of websites being deliberately made slower on Firefox. I don't think it's unreasonable to think that this will continue happening. If you do, then let's agree to disagree.
> but you are advocating for basically a free for all, and we've seen how that works.
I'm not advocating for a "free for all." I'm advocating for a "free for the knowledgeable & responsible." I'm advocating for informed consent in computing. We've been moving away from that, more so because of greed than goodwill.