is this really relevant anymore now that AI has gotten to the level it has? what used to take weeks to setup now take days (react, multiple backend services and infra)

Very relevant, because it typically takes a lot less code to express a feature in Rails/Hotwire than it does in a SPA with a dedicated back end. No need to maintain API contracts or ensure your UI code is properly async/awaited, etc., etc. Whether its a human or AI writing the code, SPA's add considerable complexity that just isn't necessary for most web apps.

Lower LOC to express a feature means better context management which pays dividends for things like code review.

This "feels like" first sentence / "curious if" ending question patterns seems to be coming from some LLM? I have seen the same across several online communities suddenly and frequently as of a few weeks ago. Notably the use of "I've seen" and "feels like" suggest the model is either prompted to act as a person or is one of the older models not strongly trained not to.

Nah read my own comment history. I tend to phrase things this way a lot too because it positions it as opinion/curiosity rather than arrogant / confident statement?