I'm still using old.reddit.com instead of the modern rework because the old version is fully compatible with Vim browser plugins while the new one has all kinds of issues with keyboard-focused usage.

This is a frequent symptom on websites that consist of more JS than HTML: they often won't even let you scroll the page without a mouse, let alone have UI that's visible to plugins(I never tried it, but I'd bet these same sites would also appear basically empty to screen readers etc.).