Monitor on before computer

[IdOp]

A couple of weeks ago my old CRT monitor gave up the ghost . It's now been replaced with an LCD panel. In the manual for the new monitor it says that it's very important that the monitor be turned on before the computer is. I've read such statements in other monitor manuals before too.

Does any one know if this warning is true, and if so why? What bad thing could happen if the monitor is usually turned on after the computer (in particular the graphics card signal is present)? I've googled this and found nothing.

FWIW I usually didn't obey this rule with my old monitors, and they seemed to live a reasonable time, but with the new one I'm trying to obey it for now.

Thanks for any insights.