You're right that vertical resolution is just one factor, but streaming uses radically more efficient codecs than DVD, so at typical broadband speeds, streaming 480P on YouTube will look far better than DVD did.
I encourage you to try it. Because I wasn't sure, I already had (using the new 28 Years Later trailer) before I posted. You can use yt-dlp to see that the 480P YouTube version is AV1 at 572 Kbps, which is notably better than a DVD Video-compliant MPEG-2 encode from the highest quality source available.
Wikipedia say that "Typically, the data rate for DVD movies ranges from 3 to 9.5 Mbit/s" [1] which is much more than 572 Kbit/s. The Youtube quality issues are easy to spot on highly dynamic clips (with fireworks, flashing lights etc).
