It's just that it's going to cause heartache in the future when the gaming rig dies.
Gaming is more likely to kill the gaming rig IMO, heat cycling, electronics don't like it..... well as far as they have likes, the mechanical strain of expansion and contraction cycles can fatigue solder joints.
If you have a 20 GPU mining farm, one or two are gonna die on you, them's the odds, but for an individual GPU, that is in the first place stable 24/7 on the settings you run, then I think the odds are better of it lasting 2 years of mining, than being hard gamed on every night for a year and turned off all day.
Similarly I know people who want to save the planet, 50 cents (per year worth) of electricity at a time, and have their HDDs power down the second they aren't in use... funny, those people seem to need to replace HDDs wayyy more than me. (Haven't killed any drive I've bought new in 20 years) Pretty sure that's a net environmental loss, just on the energy required to make the alloy casing.