What's the deal with spelling out numbers and then putting the arabic numeral in parentheses?

I suspect the origins of this practice derives from when legal documents were typewritten (i.e., on typewriters, not computers) or typeset, and anal lawyers wanted to avoid the risk of typographical errors leading to misunderstandings. But now that we're solidly into the 21st century, I think we can safely abandon this practice. I don't think any of us -- particularly us really smart FTers -- are going to be confused if you write "one" or "1" and not both. And if you accidentally type "2" when you meant to type "1" you can use FTs nifty edit function to fix it (and it's not like typing "one (2)" would have solved the problem; you'd still have to go back and edit your mistake). In my profession, I find that this practice is perpetuated by (1) very junior lawyers who think it gives their documents an air of professionalism or (2) more senior but very dumb lawyers who follow this and other pretentious practices like always putting "esq." at the end of their names.  more