@F91G this question is for you, is disabling graphic cards backlight add any meaning to watt consumption I mean those lights can even take up to 10watt combine maybe I'm wrong but I've never disabled my GPU backlight since u bought them.
Every watt saved is worth it a single 1660 GPU runs on 50watt from wall when mining Ethereum, imagine having 10 GPUs with backlight on and you off all those 10 backlight you would end up saving alot, even if it's just 5watts each that's 50watt.. this doesn't matter to you maybe because you have free electricity or green energy?.