I think we're kind of dancing around saying the same thing for the most part. Lots of armies have lots of flexibility and very little stuff that, if left out, means you have little chance at winning. By the same token, most armies have items in them that are demonstrably better than other things in their books. Still even without those "better" things, most armies can still put out a pretty solid list. A few armies, most notably Tomb Kings, but also perhaps Lizardmen and Beastmen, have very little room to be flexible while still being strong and are sort of pushed/forced into taking the "really good stuff" just to get to a base level of competition that other armies enjoy. Another way to look at it is that the size of the targeting reticle for other armies is much larger, allowing for less precision while still achieving a good hit, whereas for TK, Lizards, and Beastmen if you want to score a mortal shot, you need to get dead center inside a tiny targeting reticle.
I definitely agree with that. The one benefit Lizardmen have over the other armies you mentioned is that their "good" list is actually fairly competitive, but its definitely very boring, very mono build. Not very much diversity.