When I first got into using Linux around the turn of the millennium, XFree86 was still in use, with the associated use of the xf86config command to manually set everything up, and the warning that entering incorrect sync values could permanently damage the monitor stuck with me.
This answer explains the mechanism by which that happens, and points out that monitor designs derived from TV designs should be protected from that problem by the circuitry needed to safely deal with noisy TV signals, but that left me wondering.
How common was it to use a vulnerable design at various points along the timeline?
(And, as a subset of that question, given how ludicrous an idea it is for a modern LCD to fry itself in response to invalid input, at what point did it become safe to assume that all newly manufactured displays had such protection? It makes no sense for LCDs to be vulnerable to an artifact of how CRTs work, but did CRT monitor manufacturers manage to reach that point before LCDs took over?)