Because, and I don't know if this is a problem for others, in the pm's, sometimes the site likes to glitch out and erase words so that's frustrating. Plus you don't get notifications to your phone so that's also frustrating *shrugs*
There's also the fact that writing on mobile is difficult due to the typing glitches plus the fact that you think you're writing a lot but it turns out short. I have to write my responses in the notepad on my phone then copy and paste them here so I know I'm delivering a good amount