Also it could be a before and after-type photo. You might be on the before side, highlighting what people could lose.

Kinda wondering what OP was taking pictures of that could be used alongside an article about crystal meth...

basically every ad agency, ever.

People buy the rights to them, get them without the watermark and use them for ads and billboards

Is this a serious question? Every ad agency (like 6 said), journalistic outlets, and thousands (if not millions) of other sites use them, and I'm not saying this because I happen to be a stock photographer. There are many kinds of stock photos. If people never had need of stock photos, there would be no profit in being a stock photographer.

You don't really get what stock photography is, do you?

A stock photographer takes photos of things and uploads them to stock sites like Getty (and its subsidiary, iStock) and Bigstock. Simply put, if a photographer takes an image of a recognizable person, a model release must be signed by that person. If a brand appears in a photo, a property release is required. The same goes for certain major landmarks or monuments. If neither can be obtained, it is for editorial use only. OP most likely signed a model release.