It appears the great and knowledgeable Icculus has fallen from grace.

I really don't understand how your proposed rating system would make sense. Shows don't happen in a vacuum (though sometimes they include a vacuum). The band has existed for 40 years and there have been high and (relatively) low watermark points within those years. The vast majority of fans would agree that 2009-2016 was a weaker period than 2017-2023, and one could even argue that 2021-2023 is at a higher caliber altogether. So, when you listen to a show from 2023 that has a 4 rating, that rating should exist in relation to a 3-star show from 2010. Though the rating system is obviously flawed and imperfect, more often than not those ratings provide a solid reflection of what's to be expected. A 4-star show from 2023 is simply going to be more compelling than a 3-star show from 2010. And even if the 2023 show is one of the lesser shows when compared to the other shows during that tour, it still doesn't make sense in the broader context to rate it lower. For example, even though 12/5/97 is one of the lower-rated shows of the '97 fall tour, no one in their right mind is going to give that show 1 star.