Someone has to do it.
I'm also tired of the expectation that she has to sell with every album like she did for 21. Especially when their faves can't even sell a third of that.
The reason the Swifties are bitter towards Adele is stupid, but obvious. They know Adele is a threat to Taylor's "throne" (though Adele never really lost her spot anyways, she just went on break). If Adele had released last year, the 1989 era would have gone a lot differently.

They know she very well will likely outsell Taylor, take the attention/hype away from her and become the most talked about popstar on the planet again. Also the media will compare the two as well (as they always do, especially since the two of them are at the top) and no one is going to prefer Taylor over Adele.
To sum it up, this is all very serious business to some people! It's the same reason they hate Katy. Katy was the "top dog" at the time and they wanted to see Taylor tear her down.
Because at the end of the day there really is no difference between Katy Perry and Taylor Swift when it comes to artistry.
And they'll champion for Adele to fail too.