Not used responsibly? Hmm... I will rip a bluray disc, convert to HEVC while cutting it down to 720p with a low-ish CRF value (that is, low on the quality side, better for compression) which cuts down bitrate, and therefore the resulting filesize considerably. I've even done DVDrips in the same way (though I do not reduce the resolution of DVD video any) and my rips look perfect on a 50+ inch TV. Image quality is very much a concern, though, because I spent a very long time arriving at the process I use to transcode video to achieve the best results.
What about maintaining bitrate? If you have a 5000kbps video, and you have a new codec that can give you the same quality at half the bitrate, why not go with a smaller video? You can only push quality so much. There are a lot of "plebs" who would welcome a new codec that can chop bitrate in half without sacrificing quality. Ask anybody with a data cap and/or slow internet.