The counter proof is TV viewing skews extremely old, and there's plenty of elderly who've been staring into 60Hz screens for multiple decades with no obvious TV related illnesses.
To be fair, there is a significant perceptual difference in flicker between a 15KHz interlaced display, and a 31KHz progressive display. With interlaced video, the flicker is distributed across the scanlines, whereas a progressive display will seem to flicker the entire screen at once.
Edit: added "seem to", as I'm fully aware that CRTs scan the tube rather than doing anything to the entire screen "at once".
You are typically not watching them at the same distance either, and the fact that TV screens are interlaced might also affect the flickering effect (I understand 1990s monitors weren't).
I remember that my 67Hz macintosh monitor was really stressing my eyes as a teenager, while I never had this problem with a TV.
My first computer was a TRS-80 Color Computer 2. Neon green screen with "black-ish" text, 32 col x 16 rows. Cursor was a rainbow flashing block. I'm still not certain whether someone with epilepsy couldn't be triggered into a seizure by that screen...
Now imagine being 10 years old, and having that in front of your face while coding in BASIC, glowing from a 19" TV mere inches in front of you...hehe. That was me!
I won't claim one way or the other to not have suffered damage of some sort - I'm really not sure.
Strangely, my mom always complained to me about "sitting to close to the TV" - but had no problem when I was in front of this thing for hours on end, typing away, etc.
You're misunderstanding interlacing. Interlacing was a way to still keep 50Hz (or 60Hz in some parts of the world) while having twice as many rows. It didn't give you a higher refresh rate than that.
No, but the difference in scanning pattern does provide a quite stark perceptual difference between 15KHz interlaced and 31KHz progressive at 60Hz. The scanning of fields seems to provide a higher chance that field 1's bottom lines won't have disappeared by the time the monitor is scanning field 2's bottom lines. Of course, it's largely dependent on a monitor's specific phosphor persistence, and why high-persistence monitors were so common in the earlier days of personal computing.
Edit: added "seem to", as I'm fully aware that CRTs scan the tube rather than doing anything to the entire screen "at once".