Those two games are more popular on PS because of the exclusive DLC, early access etc that Sony paid for many times over and over. Go back to the 360 days and that was THE place to play COD because MS had the early DLC etc. Only difference is MS only locked DLC away for around 30 days or so, Sony signs these things up for as long as the developers will allow. Sometimes upto a year.

That alone makes the fact that Sony are throwing all their toys out the pram about the possible merger even more outrageous. :)