It works exactly the same on Freebsd, Linux, windows, whatever
I bet people who work with multi-vendor networks know that. One small mental note, I only work with Windows platforms.

I have never ever seen network equipment that's only manageable if you use a certain OS
That's not really the point here. There's some pretty nice third-party switch management software that I've seen that may not run the same (or run at all) on hosting servers with different OS's (like OpManager). This is something that may be important to consider in a mixed-vendor environment depending on what you're looking for.

The great thing about TCP/IP is... is it's OS independent
No way!