There are lots of ways to see ram usage in games. Most performance apps do it, although some of them include virtual-memory too, so you need to be careful how you're analysing the 'use'. Other ways include in-game (Warzone, etc, has this capability).I am not sure how much it matters YET, it is a hard thing to quantify as you can't measure memory pressure without in engine tools or 2 identical cards with different VRAM (Which doesn't exist now that Nvidia killed the higher ram variants)
However the part that sucks, is that the 1070 in 2016! had 8GB. No change in 4 years.. come on..
If games dont require it I'm fine with not eating additional cost for some rocks to be stuck on my card for no reason.
This weird focus on 'bigger = better' with RAM is bizarre to me.