And again, Ryuko has it before I do.
I don't really see this as a morally complex topic

.
EDIT: Alright fine Star, if I must get into it further...
Maybe I didn't word this correctly. Maybe what appears to be my initial post really says "GO WRITE TO WEBCOMIC AUTHORS OR YOU'LL CONTRACT HEMMEROIDS! EXTREME ONES!" If this is what my post really says, please let me know so that I'll be aware that I don't know how to read.
But on the chance that my post actually does say what I think it says: This is just a matter of getting to it. There are plenty of webcomic authors I like and whom I like the work of. I just don't bother writing them to tell them about it. There's no reason I don't, I just don't. I don't even consider it.
This is a thread about considering it. And then, after you've spent hours and hours weighing the positives and negatives of this decision, perhaps actually writing something to them. The point of the thread is to point out that yes, you can write something nice to someone, they probably won't mind, and you're letting your opinion of their work be known to them.
This is only insincere dependent on the attitude of the person reading the thread. If the person reads the topic and says "Uggh, well
okay, I guess. Geez, what a pain in the ass. I gotta' write fanmail to people and arrgh, it's such a hassle", then don't do it. Doing so then would be sincere. But if the person reads the topic and says "Hey, y'know, I do like this one author's comic, and I wanna' tell 'em that. Maybe it'll brighten up their day and let them know their work is appreciated at least by me", then do it. That's sincere, it's just that the topic was a catalyst.
If you're still sour over it, then blame Ian Jones. That's what I always do.
A man with nothing to offer and nothing to lose.