I pretty exclusively read webcomics on my PC. I dislike reading comics on a phone and I'm in front of a computer most of the time anyhow.
That said you may get a skewed result asking here. Many people who use the forums are likely to be using a PC, a keyboard is generally more comfortable to type on that a phone, for example, and many people on the forums are artists and likely use a computer to draw or edit their comics. The main reason to make stuff mobile friendly is that many people don't own a computer but do own a smartphone. Those sorts of people aren't as likely to be on the forums though.