Whatever your brand is, you will lose followers if you say you are great at something but you actually don’t deliver. Even seemingly trivial mistakes can alienate the public. A fly in a soup at a restaurant can be catastrophic (because food is their brand). A misplaced gas tank in a Pinto? some might say that was the beginning of the end of Ford’s credibility (because cars are their brand).
For librarians who claim a special knack in literacy and research, basic spelling and grammar errors do not bode well. I looked at the site in question and there doesn’t seem to be errors “abounding” (maybe in the comments?), but the principle is still the same. Be good at what you claim to be good at or expect to be marginalized.