They were used all the time! And the new hotness is octahedral impostors, or other such tricks. https://www.shaderbits.com/blog/octahedral-impostors​

You can get shadows from these things, pretty fast too. Which is important as missing shadows are actually more noticeable than the difference between the impostor and actual geo if you're far enough away.

That being said, my take is to have a volume texture. Raymarch through it, very fast, and store 8bit channel as “opacity”. But instead of doing translucency you use russian roulette modified by the value, ideally modified by a blue noise texture too (that requires doing taps over screenspace but it should get rid of noise), to decide whether you hit or not. Thus you essentially have alpha tested volumetric impostors you can do shadows and even self shadows with. As long as the volume texture meets, or exceeds (thanks taa) the relative screenspace texels its projected onto it looks good.