The reality is Comic Sans is awful to look at. But the big problem is its ubiquity because amateurs are drawn to it, much like Papyrus.
Honest question: Why? What does this even mean? What makes a font "awful"? Surely this is a matter of personal taste and/or collective fashions?
I guess I'm an outlier since it's become cool to be a font nerd, but I really do not give a shit about typefaces. Except for difficult-to-read cursive scripts, pretty much everything looks fine. I find it difficult to conceive of how so many people get so worked up over this stuff.
I think the reason the Internet hates it in general is mostly because of its use in inappropriate places (I even saw a picture of a funeral announcement that used it).
Unfortunately, most people do not have much if any aesthetic sensibility.
If most people do not have much if any aesthetic sensibility, then perhaps you do need to be a font nerd (or a car nerd, shoe nerd, etc) to see these things intuitively.
Something comes close though. Dismissing critics as amateurs without further discussion, and also saying anyone who doesn't intuitively agree has no aesthetic sensibility (as is said in a child comment below). These substance free dismissals are equivalent to your criticism of the creator's comments.
Though, obviously, I do view them as wrong, I gave my reasoning as to why. I could go into more detail as to the exact reasons why Comic Sans is ugly, but others have done a better job than I would elsewhere.