There are quite a few issues with the original statement.
The very first arcade monitors were TVs with the RF and other unnecessary parts not fitted to the PCB.
Then the next variants, the most common, were based on TV electronics but with specifically designed chassis. Thats why they are 15Khz scan rate, as a TV, and they used TV CRTs. CRT tubes used in all the classic arcade monitors are TV tubes.
It also explains why they needed isolation transformers, as they used the same design of very simple non-isolated power supply as a TV.
LCDs will not be damaged by gaming. Plasma screen might be an issue when displaying game-type graphics over a very long period of time but not LCD.
LCDs which can accept 15Khz horizontal scan have been around for a while and are extensively used in Asian arcade cabs.
Its not the case that LCDs cannot display anything other than certain vertical scan rates such as 60 Hz etc. They do often have built-in limits but they will generally go down to around 45 Hz. The min horizontal scan rate is usually limited to 30Khz though so you cant connect a 15Khz source to a standard LCD screen, you would need one of the special 15Khz-capable ones.
But there is not really any point in getting a 15Khz-capable LCD for Mame because the picture will not be any different to a 31Khz one, and not be any closer to a CRT picture, where each scan line is a game pixel (when using native resolution). The LCD will have a large number of physical screen pixels per game pixel. If you run at 31Khz it just means twice the number of LCD pixels, vertically, than there would be at 15Khz.
Thats not to say there is no advantage in using native resolutions on an LCD screen. There is almost as much advantage as on a CRT screen, because no stretching is required to be done by the VGA card or Mame.
CRTs are almost history as eventually the last CRT tube plant will close and that will be the end of it.
Golden Tee, which are probably the most common real coin-op video machines are now using LCD.
Andy