*Disclaimer: I am very much a novice when it comes to the tech end of using a mac.
That being said what you say makes total sense - anything with the right cables will match up, some monitors will match up easier than others but my first attempt did not support your hypothesis.
Ex.) I bought a refurb ( still expensive) Apple Cinema 20-inch Flat-Panel Display thinking "if its mac it will fit", only to find out it uses a 80 nail firewire (?) where mine is only a 40 (* someone told me these numbers - I may be getting them backwards or wrong all together) - and there is no "adaptor" for that situation, so I had to send it back.
Many of these monitors need DVI, Firewire and USB 2.0 connections- which is a heck of a lot of ports! In my imaginary "easy street" world there is a 20" monitor out there that plugs into my Imac via (1) DVI cable and I turn it on & I am done. If I walk into Fry's , or one of the better electronic stores with my stats, do you think someone can hook me up?