How someone's daily schedule is will determine which one is preferable in usage for them. In my own case, I prefer a smartphone because I can make use of that at any given moment without any stress or running out of battery for the use of the forum.
My type of work, requires me to be active online. Because I do have a course online that I am helping out with my friends to carry on with on WhatsApp. I can't do all that with my laptop without having it switched off within two hours, while my phone lasts many hours.
The same goes for the forum. Since I am always on my phone, I can read forum posts at any place I find myself. It must not be at home, it might be elsewhere, where I am hanging out with friends. I can take a look at that post, and comment on it if I like