Erm, don't exactly agree with that. Your standard user will run their crt @ 60-120Hz (cause if ur a b!tch like me and can see flicker @ 85Hz and 100Hz sometimes, ya need a sick crt). Anyway, what happens is that CRT's have a flashing image and it is updated x amount of times per second. LCD never turn off however, as they can't- they do not have phosphors which lose energy. Rather they shift the form and position of a liquid crystal to block light accordingly. When liquid crystal is set at a certain position and form, it stays there until updated again. This is why an LCD cannot flicker. Additionally, the backlight(s) of an LCD are slow decaying decaying so despite voltage is supplied @ 60Hz and often lamps have a "doubler" that makes it 120Hz, the lights will not ever turn off.
With CRT's the "response" time of each phosphor is in the nanoseconds (so for all practical purposes we can say there isn't a response time). Now on an LCD this is a different case; LCD's have response times like 40ms, 50ms, 25ms, and the newest 16ms (and technology is being currently developed that is 12ms or less). Generally this 16ms or even 25ms response time would be fine, I mean w/ 25ms u can display 40fps sharply on a screen and with a 16ms screen 62.5 fps which is enough. The issue is that this response time is for black to white and white to black (rise + fall time) but when dealing with intermediary greys, less voltage is applied to the crystals so they have a higher response time. On a 25ms panel, the response time can go up to over 50 ms for rise only, which is unnacceptable for games and creates a blurry image. 16ms on the other hand doesn't go up significantly so that there is noticeable blur so it's fine for gaming.
In terms of light being emitted, LCD's actually emit more light. The human eye is most comfortable at 40cd/m^2, and CRT's max out at 100 or 120 cd/m^s- past that point considerably greater amounts of energy is used and the lifetime of the phosphors is greatly shortened. LCD's on the other had generally emit over 200CD/m^s and go up to 300 (and there is one with a blinding 800cd/m^s!!). This is really uncomfortable for the eye and due to the nature of lcd's, they cannot physically block all light so even when displaying black or setting brightness to lower, there still is light leakage and this often causes more eystrain than on a CRT. This factor alone can make ur eyes hurt like hell after even 2 hours in front of the comp! (and the reason manufacturers keep upping light emission is marketing- bigger number sounds better, right?, and that in order to have higher contrast ratio one needs higher brightness).
With that said, it depends on what you prefer, but imho, a flat CRT set at 100hz or higher will give little eyestrain. I currently use an NEC FE791SB and at 116Hz, I don't feel it when I sit in front of it for 10 hours straight.
"If everything seems under control, you're just not going fast enough."
- Mario Andretti