EDIT: Never mind, sorry, I missed part of the article, it does indeed say what you say.

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That's the opposite of what your source says:

> In writing, however, use to in place of used to is an error.

Used to X was the standard past tense of to use in the sense of being in the habit of:

I used to fish: I was previously in the habit of fishing, correct both in the past and today.

I use to fish: I am presently in the habit of fishing, correct in the past but no longer understood today.

The second, however, is according to MW occasionally misused to mean "I was previously in the habit of fishing".