Precisely. Many people don't realise how exceptionally well JSON compresses. Provided you're using it the way most do, to send arrays of objects which share the same set of keys (or some subset thereof), then all the keys will end up dictionary-coded away, thus totally eroding the space advantage that this format notionally has.

Plus JSON's exceptionally wide support means you can benefit from SIMD-assisted decoders which will absolutely blow this out of the water – and much, much more besides. I wish people would devote their time to something more useful than 'yet another competing standard'.

Edit: Sorry, I want to be clear, this is an impressive and cool personal project. I hope it's a step on an exciting journey for the person who wrote it. It just doesn't actually have enough strengths to replace JSON - which would be a tall order for any new format.