It's hard to explain, but important to understand a bit about editing and proof-reading. If there was no one to "proof" articles, the finished product would be an embarrassment to an editor and to an organization such as the Photographic Society of America (PSA). Here are a few remarks and comments on the matter of usage in the Journal.
Writers using a word processor generally use the built-in spelling check system of the software. The Spel-Chek will catch an error like alot. Most writers using alot, meaning "a lot" of something, have made the exact same mistake for years--still, there is no such word. Some writers will mistakenly change this non-word to allot because the Spel-Chek told them to change, but allot has an entirely different meaning.
It goes without saying that the proofreader must know the difference between to, two and too because some writers don't seem to know and a spell checking system doesn't recognize the use of the wrong word.
It becomes clear then, that when writing it is probably not sufficient...