Even though I told you don't ask me why.. you're asking me why. But I'm a good donut so I went back:

They dont have to press BOTH keys to press space, they just didnt have a spacebar key that is the correct size to fit, so they put those 2 random keys on instead until they get a permanent keycap set that all fits.

Less used than the Code key apparently. Their editor must crash A LOT if they need a dedicated button to launch it more than A or Space

They meant to say "Control or* Backspace is Space", right? Right?!

Uniqueness

Split spacebars are thing mostly because of layouts that won’t support a normal spacebar key. But, since most of these keyboards have user created and designed firmware, one could assign those spacebar keys to do anything.

I have a few keyboards with split spacebars where the “right” spacebar is normal; it’s just a spacebar but small. The “left” space does dual duty; tap it and it’s a spacebar, hold it down and it becomes a modifier key for a custom layer. Custom layers are used on small keyboards to make the “missing” keys available, sort of like how a phone keyboard has number layer and symbols layer.

I fully embraced this habit of split spacebars because I cannot train myself to use my left thumb to hit space for the life of me even though I’m a touch typist. Since my right thumb is the only digit hitting space, may as well get some use out of the rest of the space taken up by that spacebar.