Why Orange vs Blue?

I've noticed that several Moba games use these colours for opposing teams rather than the traditional Red vs Blue.

Is there any particular reason for this?

If they used red and blue people would complain they copied TF2. Orange is also brighter and easier to see.

I've always thought of TF2's colours as being more red than orange.

I take you point about visibility, though.

Diamond vs Pearl

I think orange just stands out a bit more. That and it's also the polar opposite of blue.

This pretty much.

Orange and Blue are kinda dynamic too, you can have as many orange combinations with blue and they still look good if I am correct.

Orange vs blue lets you discern colors faster. Sure, unless you're colorblind, red vs blue isn't that hard to notice either, but orange vs blue is nearly instant, because of how they make each other pop out, so as to say.

Is it just me, or in SMNC are the Hotshots red instead of orange? If not, I guess the color correction of my PC is terrible. x.x

Are orange and blue complementary colours?

EDIT:

Yes they are