GPUs also do not like overdraw, so it's generally good idea to avoid having many transparent elements on top of each other, its also the reason why drawing more triangles vs. transparent texture is generally better.
My big take away with the whole City Skylines 2 performance issue and the lack of LOD was that geometry processing is so cheap nowadays. So long as you aren't too reckless with geometry in terms of sub-pixel rendering, you don't really have to worry about it too much any more.
It isn't like the Ps2 era when geometry time was a real concern on render times. Even a modern low end GPU could process a few hundred million polygons a second without sweating it, now getting the result son screen is a very different issue.
Yeah, PS2's Graphics Synthesizer had a fill rate of 1.2 GB/s. For comparison, the OG Xbox had 0.932 GB/s, and the GameCube had 0.648GB/s. Assuming only 1 texture here.
The Xbox was released 1 year later, for context.
Sony also demo'd the GSCube once, it had 16 Graphics Synthesizers, achieving a fill rate of 37.7 GB/s (no textures, half that with 1... I think). Eventually they ditched the idea in favour of Nvidia's solution.
