@xorangekiller Thanks for the links. It isn't necessary to establish that all movies ever done are made using Linux "desktop" software and render farms, only that viable options exist and you've done that.
I guess the second part of the question is "So what?" This line of argument (that "Houdini is really good and works on linux") doesn't really appeal to anybody outside of a large visual effects company. It seems to follow the same argument that Mac users used in the 90s "Photoshop is way better on Mac OS 8 than on Windows so everybody uses it" or "Only a fool would even consider doing page layout without QuarkExpress/PageMaker on System 7." Today you might find Windows user making a similar claim using Solidworks: sure it runs on Mac OS X but nobody does it and Windows is clearly the best platform for that tool.
Linux users can easily grant those claims and point out "but even engineers don't play with Solidworks at home: they just browse the web, watch movies, and ship cat photos to grandma." It seems like the reverse strategy would work here too: "Linux has great software if you've got a $100 million dollar visual effects budget to spend…the rest of us are not convinced." It's not like anybody is going to be using that stuff to jazz-up their Christmas morning videos, though you might expect them to do a bit of editing using iMovie, Windows Movie Maker, or maybe even FinalCut/Premiere if they're particularly video-edit savvy. Are their compelling replacements for applications like WMM/iMovie, entry-level NLEs like Vegas, or FinalCutExpress?
Openshot and Pitivi are good easy to use basic video editors similar to windows moviemaker. Not sure about higher-end video editors, but lightworks is coming to linux in the near future.