Power use = heat, more power use = more heat.
Air conditioning and fans(appliance) will need to be ran for longer periods(possibly lower temperature setting for AC too), or one's room will heat up faster if there isn't a means to exhaust the heat produced from the PC immediately out of the room.
There are various circumstances: Cost of electricity isn't a drop in the bucket everywhere, and not everyone is well off. People live in various climates, from hot/cold year round, and temperate.
Liquid cooling isn't a fix.
Ryzen 3000/5000, Nvidia's Gpu Boost - I think AMD's RDNA does it too - cooler thermals increase power use, albeit very slightly.[As far as power limits allow, anyways.]
It doesn't matter if one is getting cool and frosty thermals if 400w or whatever is still being dumped into one's room, instead of directly outside.
As someone who lives in a subtropical climate, summers get toasty. Late spring and early fall can be rather warm too(pushing 29C/85F outside).
Between the top end AMD and Nvidia gpus, I wouldn't enjoy a very big heater(3090/Ti) running very much during the summer - winter would be another story.
Excluding the transient spikes, there's about 100w or more between them and the smaller heater(6900XT), which isn't that far behind in raster performance.
100w or more is significant - to me.
Cpus typically don't use that much, save for blender renders and similar. Besides those loads, their power use has been way behind that of gaming gpus.
Fortunately, I have access to air conditioning and electricity is cheap where I live, but I'm not loaded, so I'd say power bill and heat are tied for the biggest concerns for me on the above list.