I think you're more likely to see an effect if you can somehow capture how far a solo founder gets before they need to bring on the second employee. Because LLMs aren't better than me at my job, but they are better than me at many jobs which I can tolerate being done poorly.
If there is a significant technological shift, it'll be when those startups start outperforming the ones for which LLMs weren't available at the start.
And as for the js ecosystem craziness; while I agree that we went through a lot of craziness, I think it was necessary to arrive at the current relative stability around React and a handful of other frameworks in conversation with it. React in particular was originally released in 2013 and definitely benefitted from baking outside in the sun since then.
Or Contextual Shared Variables
Or eXecution Model Language
or..