Lack of CRT flicker is the biggest problem. Demo text scrolls are far more readable when you don't have sample-and-hold blur. There are gaming monitors with strobed backlights but I don't know of any that allow you to enable the strobing at 70Hz.

A workaround for modern hardware is frame doubling then blanking every other frame (software black frame insertion). It halves the brightness, but modern monitors generally support higher brightness than CRTs so this just brings it back to the authentic level. It's possible with FFMPEG filters, although I don't remember how I accomplished it when I tried it years ago.

The importance of CRT flicker is one reason I greatly prefer DOS demos to C64 and Amiga demos. Those were mostly designed for 50Hz PAL CRTs, so the flicker is far more annoying than 70Hz VGA.

I mean even these browser ports aren't at the native framerate. The native framerate for these demos was 70hz as they were all designed for VGA video modes.

A browser can run at whatever framerate you set your monitor to. Mine supports 70Hz.

But most people’s monitors don’t, or people just never set them outside the standard rate.

My monitor's standard and actual rate is 165 Hz, which is probably not terrible at approximating 70 Hz (very few fps from a small multiple of 70 would be worst).

High fps is probably a little more rare than HiDPI, but also becoming more common. It's already common in phones.

Sure. I don't think I've ever had an LCD monitor that supports 70hz at a useful resolution though. My current monitors (native resolution 2560x1440) only seem to support it at 1024x768!

Well, the demo runs at a lower res than 1024x768 so you're all set ;)

I would just run it on my 386 with real CRT anyway haha

Pretty much every modern fast gaming LCD will support 70Hz.