Consult this video, for example: https://youtu.be/sCv-dIFGcd0
Personally I find that even BD-rips made in SD resolution look better than DVD—if only for contrast enhancements made for reissues, and due to better compression formats.
Moreover, if the source was shot on 70mm film then people might still keep re-digitizing it in the 22nd century into fresh HD formats of the day.