I can only talk from personal experience, but it absolutely does speed up things. I know because I went from working away at one project to progressing many projects at the same time. Starting up new projects I never would have bothered to do in the first place just because the work would have been so tedious and I wouldn't have enough time in the day. Mind you, I don't vibe code things for public consumption. These are all for my personal use, but the fact that they exist at all is evidence contrary to your points.

(Important note: how I use AI in important software is very different from how I use AI for slop projects; the speedups are not as dramatic when you aren't vibrcoding and you actually need good quality; I suspect most AI usage would actually be a slight downgrade for speed unless I delegated them strictly to review and menial implementation; but that actually assumes that I know the language I'm working in very well, which isn't always the case for vibecoded projects: In those cases, the AI slop is probably equal to or better than what I would write by hand because I'm not as competent in elixir or javascript as I am in C or C++)

I feel like this is dishwasher discourse... Washing by hand is faster than the dishwasher by the wallclock; but you don't actually need to rinse as much as you probably do, and you can walk away and do other stuff while the dishwasher is working. If you just sit there and stare at the dishwasher, yes, it's slower, but that's not how people should use it, and that's what most of those studies are showing. Again, that level of sloppiness isn't applicable for all use cases, but for where it is useful, it is very useful.

Listen, I'm a VERY healthy skeptic of AI on a number of fronts, but saying it can't speed things up is just not true.

I feel like I understand where you're trying to come from with the argument about skill degradation, but the flat statement you say here is undeniably false.

"Degrades quality" assumes developers are already writing good code to start. Unfortunately that just isn't true. For people who know what they are doing and can properly guide it, it absolutely speeds up the menial tasks that plague software engineering. I'm not even a fan of the direction AI is going yet I absolutely see the value here.

For the AI haters, we really need to attack it from a better angle than "it doesn't work" because it absolutely does.