I've heard it from lots of people (and done it myself) to get rid of creaks froms the BB. It's done with grease, not instead of it. It solved my problem and didn't create others. If there's an issue with it, I'm all ears. It may be more common in the MTB world.

For those who don't know, 'plumber's tape' is thin and meant for threads. It's not like wrapping a BB with packing tape.