Look here. 3070 8GB outperforms 6700XT 12GB with ease in new games at 4K/UHD in terms of minimum fps. Minimum fps would drop very low if VRAM was an issue ->
https://www.techpowerup.com/review/amd-radeon-rx-7800-xt/35.html
Is just a bad comparison which actually tell us that 12GB @192 bit doesn't suffice for 4K, 6700XT memory bandwidth of 384 GB/s and 3070 has a memory bandwidth of 448 GB/s. 192bit vs 256 bit, 6700XT is not a 4k card it will struggle. Is 3070 a 4K card, maybe but not a very smooth experience. You compared apples with pears in same basket in but, are in different gardens.
I get your point, is marketing and hysteria, and are caps on VRAM usage in the drivers... lazy developer are at the core of this SS.
The difference between high and ultra textures is often just slightly less compression (sometimes ultra is uncompressed), which you most of the time won't notice when actually playing the game. Dropping texture quality to low and sometimes medium can be seen easily, but high and ultra mostly looks identical, especially without 300% zoom and in motion.
Yeah, lazy coders but, just those lc will make a lot of games to eat too much CPU, too much VRAM and not gonna cope with 128 bit ones either even if are 16Gb of it.
You have to be logical. Game developers knows that the majority of PC gamers don't have more than 8GB.
Is nothing logical around lazy codes, "Game developers knows" and can't give a rat ass if you have to lower your settings in order to play that game on 8GB card.
Form their point of view
you can play the game on 8gb card just not so eye candy.
For example War Thunder didn't drop yet ultra low settings so you can play the game with a 960 card, because is a "free" game? they want huge player base from which a % will cash in.
They are heroes, nope. Just an example why a dev will support low end GPUS.
Why a lazy developer of triple A game will do that? Why would give you the chance to play with your 6Gb card and work hard for that? Popularity, fan loyalty forgotten criteria not exceeding 1 % brain activity of a developer.
Just because is possible to run well coded games in 2k and 4k with 8Gb VRAM doesn't mean it will be more than 2% of such games.
Same story goes for the space that games requires now days.