Re: Is this officially what we're doing? 1990-2019/20?
I basically agree re: live albums counting, to a point: there are so many live releases nowadays that you could fill a top-100 list entirely with live Pearl Jam, and if you're into Phish (or '90s Grateful Dead, for that matter) that could take up a disproportionate part of your list. I'd be okay with excluding official bootlegs and archive releases, but on the other hand it's up to you/whomever to care if much of anything actually gets represented on the final top-100. I guess it's no big deal in the scheme of things.
Got it regarding the "EQ curve". If it's done however you like I might restrict mine to a certain number of years, too. 1980 onwards has been my greatest amount of growth and therefore change, except that most of my top 10-20 overall in 2014 was early '90s or thereabouts and, thinking of how I would put together a 1990-2020 list, the top spots would still be mostly early to mid '90s (the top of the overall and restricted lists would be similar, in other words.)