I'd posit that the reason is a nuance of #2, more thought was put into older code on the design of how it should work before making it work. Now we write code so fast that we have to scrap it all and do it again a second time to fix the mistakes of the first time [0]. I'm of the mind that upfront planning would've likely taken less time, but that's simply my opinion and I don't have anything to back it up besides anecdotal experience. The current practice of "move fast and break things" very well could be a better approach.

[0] I'm only mentioning this footnote due to the article picking on Angular (fairly or unfairly), but the point I made that this is footnoting is relevant to them potentially.