It's only objective if the selection process for top conferences is objective. But I do appreciate a metrics-driven system vs the surveys that US News uses.
It's unfortunate that this might seem esoteric / insider-baseball to non-academics, but researchers in CS know exactly which are the top conferences. There is actually very little ambiguity.
Looking at the list, the entries for Robotics, NLP, Computer Vision, and ML are accurate, to my knowledge (I would also include UAI/AISTATS, but they were probably omitted because they're closer to mathematics/statistics).
Being a CS academic myself I fully agree with what you just said.
That said, the decision that they should the top three conferences (as opposed to the top 2, top 5, etc) in each area is a subjective one, and has the potential to significantly change the results.
I don't think they're just listing the top 3 conferences. It seems they're listing the conferences that are considered "top" tier conferences - e.g. venues that would "count" for graduation as a PhD student / consideration as faculty, at a top-10 CS uni.
The conferences listed (at most three per area; see
below) were developed in consultation with faculty
across a range of institutions. These are the most
impactful and selective conferences for each area.
I think there is still some debate as you highlighted in your own response. For example, I would argue that ICDE could also be included in the database group. Perhaps even EDBT/ICDT. Still, I would agree that the conferences which are included are probably a good proxy anyway.
