The "why" in all this, sadly is people can be jerks. I suspect those that pick on Shannon are jealous that her work garners the attention it does and somehow, for some reason, find her an easy target for their vitriol. People feel mighty tough behind a computer screen.
If people are going out of their way to criticize her, it means she's doing something right. As the old saying goes, you know you've made it when the haters come out. I'm not sure how she feels about the haters, but I know I both laugh at and welcome mine. If someone wants to take the time to read my stuff and tell me how much of a piece of shit I am...have at, I get paid by the read, so than you for your generous contribution to my wine and treats fund. If they want to take it one step further and write a hit piece, yippee, go on and drive more traffic my way as the curious come on over to see what all the fuss is about (again, I get paid by the read). These bullies are so stupid that they don't even get the fact that they're making her more popular, not less. Shhhh, don't tell them.
I've not donated to her fund, but only because, at the moment, I'm not in a financial position to do so. But should that change, I have no issue with doing so.