On there other hand there are users ,who appear to have little or no knowledge of digital compression, who are running very recent H.264 encoded videos through a free program they downloaded from the net and re-encoding them with a H.265 codec, often at a different resolution, bitrate, frame rate, colour space.... The resulting videos are of a much lower quality, as anything encoded with two different lossy codecs will always be. Obviously if you're watching in poor light, on a phone screen covered in fingerprints you won't notice much difference, and I was told off recently for being old fashioned because "everyone watches porn on their phones nowadays", so maybe I'm just out of touch.

My worry is that the original quality torrents are dying while these substandard versions are flourishing and that's frustrating

It's getting so hard to find good quality copies of videos because of the amount of low quality re-encodes flooding the site

They are ruining the original format and codec: [unfortunately ]
Oversize upscaling w/ non standard format ...
To boost up their ratio ...

There are a couple of users that are producing good re-encodes, but generally, I agree with you.