I've looked at a few forums that removed copyrights lately, and of them and ones from the past, more have been using the Mambo integration than not - and this is while, in my experience, most people who use SMF don't use the integration (as much as a lot do, the proportion is different.)
Thus, it is my conclusion that for some reason people who use Mambo think that the terms and agreements that apply to Mambo and/or its copyright statement apply to SMF. This is not the case!
Anyone know why people think it's okay? Clearly, it is no different than thievery - we ask you to pay a simple price for using the software for free.