Computer science doesn't need journals because (1) It's generally easy enough to reproduce any work you care about, so you don't need to take anyone's word for its correctness, and (2) researches can make a fortune in industry doing their (profoitable) work or something related, so the don't need to suck up prestige factories in order to get funding.
I was thinking as well that its less abstract. Biology research takes a lot time and of work to filer through to practical applications. AI research is generally doing something practical straight away.
