I'm not sure what I should answer here, but I'm invited. I always use SCSS. Can't say why some don't, maybe it's not complex solutions, why add complexity then. If you use BEM a pre processor isn't that necessary.
Did some googling and it sounds like BEM isn't specific to CSS or Preprocessors and is just a methodology so if that is the case it doesn't apply to this topic in any way. Thanks for the odd input though.
I agree with @emilmoe . @iSamuelBarney You have no right to invite people to answer and then try to offend them. Even if you disagree with @emilmoe @smirnov and @Robert you should be gentle in your replies. Don't be rude as this is a friendly place for developers.
@emilmoe @carolfoley_dude I'm sorry if it came off as meaning to offend that wasn't my intention, I simply speak my opinions openly and unfiltered. The developer community is full of one sided opinions, friction between competing viewpoints is a must if any real insight is to result. (at least that is my opinion... lol) I will try to be extra gentle when in a discussion with you two then in the future and will make a note right now of your emotional needs when our views don't perfectly align.
Unfortunately there are 1000's of developers just like @iSamuelBarney that don't think speaking to others in a respectful tone is necessary or worthwhile. They think speaking to others condescendingly is simply a way to prove that you're more correct in your opinion. See how I'm speaking as if he isn't here? It's kinda what it feels like...