I think the larger point of the OSR is there is no “essential material; no top tens, nor bullet lists, nor cliff notes that someone can skim/speed-read their way through to a journeyman understanding of the game.
The vibrancy faded as soon as it passed from confirming assertions made in the original works through play (as opposed to the read/speak/read cycle), and discussing what play confirmed, to producing commentary that is to playing D&D what Cosmo articles are to sex: ten things I think this year’s crop of college freshmen should think, written by college sophomores, and surrounded by 271 pages of advertising