Technically speaking, the word “as” probably is redundant, but I think the phrase should simply be seen as idiomatic. It is widely used and is typical in the sort of context your sentence illustrated. When I write “typical” I mean “usual” or “normal”. It is also worth noting that the author of the website didn’t actually recommend using “in accordance with” – that was simply given as the definition. Ultimately, the recommended sentence excluded both phrases.
Tom, you will find plenty of disagreements about plenty of things in English. Some experts will tell you A is correct, and then other experts will tell you B is correct, and then still other experts will tell you that only C is correct. And it’s quite likely that A, B and C are all “correct” to one degree or another. :lol:
I noticed that the website also had the word “issue” listed. The use of ‘issue’ to mean ‘problem’ is relatively new and I myself still laugh at it because it often seems to be nothing more than a denial of reality: There is, in fact, a problem. :lol: But this is another usage that you’ll hear and read everywhere, so how can it really be “wrong”?
I haven’t read everything on the site, but based on a quick sampling, I’d agree with Torsten’s take on things.