That’s not true in the slightest. None of Canon’s 50D and up line, 7D line, 5D line, and rebel line did anywhere near that long ago. I did not shoot on Nikons back then but I imagine most of their fleet didn’t have dual slot recording either. You’d have to get high end pro gear until 10-12 years ago for it.

The 5D3 was first, so that was like 12 or 13 years ago now. It rolled out after that over a few years across their fleet.