We're all ignorant of the vast majority of facts relevant to almost anything. Comprehension is expensive and scarce. That being the case, simple extensions of good faith count for a lot.
As much as I'd like it to be true, looking at a bunch of .gifs about quantum mechanics and astrophysics plastered with white majuscules does little for one's understanding of science. In other words, IFLS is to the scientific community as r/atheism is to the religious-sceptics community (not the best analogy...).
The problem arises when people share untrue information out of the notion that they're spreading science. Comprehension is indeed expensive and scarce, which means recognizing the borders of your own knowledge and the start of your own ignorance is extremely important. Pseudoscientific drivel has no place anywhere.
Whereas the facebook page does nothing like this at all - it's just funny pictures with a theme. It doesn't encourage any way of thinking or promote figuring out the world.