My argument isn't "this is complicated so let's not"; it's "this is complicated and needs to be handled with care, not with a trivial attempted fix like 'dumb pipes only' the way people often seem to think". Together with a healthy dose of "regulation has historically failed to adapt to future technologies". And we don't really want regulations that privilege the tech we currently know over the future tech we don't; that tends to lead in unpleasant directions, including regulatory capture and blocking of future competitors.

I think the fundamental problem here is that in most locations we don't have a market at all, free or otherwise. We're looking at all these restrictions in an effort to work around the fundamental problem of "people have little to no choice in ISPs". If you're going to have one ISP in an area and regulate its behavior heavily, you might as well just have the government run it. (Note: that's not a recommendation.)

I'd be entirely in favor of solving the problem by saying "last-mile infrastructure (from customers all the way to the nearest meet-me room) is a public utility, all ISPs have to remain separate from the last-mile infrastructure". If the average customer had a choice of half a dozen or more ISPs, none of these problems would arise, because any ISP stupid enough to make services deliberately worse would get dropped in favor of ISPs that don't. ISPs could then compete on everything from services provided, customer service, neutrality, geek-friendliness, IPv6 availability, CDNs/mirrors, or anything else they think people want.