It really doesn't matter how much you optimize because I have big hands and phone screens are quite small, which means no matter how amazingly you optimize it, and how responsive you think it is, the screen size of a phone itself is not big enough to justify me playing there. iPads are a bit better, they are bigger in size at least and I can understand that but I never used it, well I used it before at my friends and all, but never owned one because I never needed it so far.
However, if we are talking about PC? Well that is just perfect, huge screen, total control, everything on screen. It's just unfair comparison and my choice is clear in this regard.
That's why we have different preference when playing and in your case you're more comfortable in desktop. Well, I don't usually play in desktop because i'm often at work, so mobile is suited me the most especially when at home I like the idea that I can gamble while lying in bed. Rollbit has a user friendly mobile version the reason why it's not a problem for me to play even in small screen.
I never assumed that it wasn't based on preferences, and situational preferences is a real thing as well, like lets say even if you preferred PC in general, when you are at work or at somewhere that you do not have access to your PC but have free time, mobile phone is the way to go.
I just wanted to point out that if you are capable of playing on your PC, like lets say you are at home and you have nothing to do and you can open up your PC and open up your phone, both are possible, there are STILL people who prefer the phone option. That is true, and I understand they do, I just do not understand why because it's visibly different and much bigger with details on PC, it's fine though, maybe it's just me and that's okay.