First weight. Then resolution. I think SoTA for CRTs peaked at early HD resolution 720. One might be able to modulate the beam faster now. Size. And safety - anyone starting up production now would have to solve the safety issues from scratch. Nothing like a few cubic feet of vacuum imploding to ruin your day.
xyzzy_plugh · · focus · HN ↗
phkahler · · focus · HN ↗
lstodd · · focus · HN ↗
then there was Iiyama Vision Master Pro 514 with 140-ish kHz horisontal scan