Why do "artsy" web sites use second windows?

[somebody222]

A disproporiatenly large number of "artsy" sites (Flash-heavy sites that display lots of pictures) have a main page which does nothing but launch a second window. Example: supermodel Alessandra Ambrosio's official webpage: (WARNING: no nudity, but probably not workplace-safe): http://www.alessandraambrosio.com.br/
But launching that second window is detestable on so many levels -- pop-up blockers may break it, it runs against the general paradigm of web surfing, it annoys users to have to close a seperate window, etc. Futher, the window is usually not resizable, which is also annoying. The designers of all these webpages *must* have had some reason for doing it.
Given how bad this practice is, why do so many Flash-based "artsy" websites do it? I'm assuming it must be some limitation of Flash that requires launching a new window to get the full effect, but I don't understand how that could be since I've seen lots of pages use Flash in-place.
So why do so many websites do this?