This is where browsers' reader modes really help. Is Chrome the only one now that doesn't natively support reader mode? Reader mode in Firefox made this much easier to read.
I actually just didn't notice any difference in legibility and rather focused on the neat effect of the brushmarks around the div enclosing the code.
I kind of figured people would complain about this though---its an artistic sight, and not everyone is open to form over function.
This actually reminds me a LOT of making websites around 2006 - 2012.
Actually, I think it is intended to look like mechanical typewriter output.