--Investment (If you spend $2,000 on a DAW, then there are strong psychological forces at work needed to justify it.)
--History with the DAW (Most will defend their choice as better...just check the "which host is best" threads)
--Differing Pan Law settings (has fooled people in the past)
--Other differing initial settings
There are other reasons, but when someone says, "A sounds better than B" then there should be some way to demonstrate it scientifically. I've seen no one do this (and any completed test I've seen showed that audio was identical). Not a surprise.
Pretty much all you see about any DAW sounding better or worse than the others are words spouted by people "trusting their ears" and having no idea what they're talking about. I also suggest that a few of the comments for or against certain DAWs are on the payroll of some of the companies.....at least, it wouldn't surprise me.
Of course, this ignores the fact that the reason our tracks suck have to do with bad lyrics, bad arrangements, poor composition, bad mixes, etc. and nothing to do the sound engine of the DAW.