This is true, but: you have to watch compatibility (note that there are no 3000 series chips on that list - because NVIDIA changed their hole placement again, and AMD has a couple different sizes for their different chips, 6500XT/6400 is definitely smaller for example), and also it doesn't do as good a job cooling VRAM. You can put add-on heatsinks on the VRAM chips, but they can fall off and short something. And adding them on the back can run into compatibility problems with bumping into the CPU heatsink.

And VRAM temperatures are a big problem on the Ampere cards - I don't really think running >100C all the time is really gonna be great for them long-term. Even gaming (vs mining) it's not abnormal to see VRAM over 100C (especially 3090, with the chips on the back, but also on the other GDDR6X cards, GDDR6X just runs extraordinarily hot). I know what NVIDIA and Micron say, I'm not sure I believe it. Above-100C is really really dubious imo.

for the 3090, with the VRAM on the back, I think it makes sense to go with a factory-configured AIO. Other cards, and especially GDDR6 cards, sure, it does work and it does help. Don't go too nuts tightening the AIO down though (ask me why! >.<)

Gelid used to make nice little cooling shields for the VRM and memory modules. I'm disappointed they stopped, although I'm sure it was a tiny market. For single-sided cards that is a much much nicer solution than stick-on heatsinks imo.

https://www.quietpc.com/gelid-icy-vision-gtx1080kit