I like to call it the
I was watching a video for Hamza Yusuf on the matter awhile ago (forgot which video, will add it later if I find it), and he explains some of the conceptual similarities between Protestants and Salafis. In simple terms, it is the concept of rejecting the tradition, and only accepting the source.
Islam, being into revelation for about 1400 years, has went through extensive scholarly studies and thinking, and has developed a rich tradition in different aspects of the religion, so much so, that I was listening recently to a review of a book of something like "140 Etiquettes of Eating & Drinking" by Sufi scholars.
Now, with such extensive studies and aspects of the religion, it is not surprising, one might find incorrect things being added to the tradition here and there. And so, every generation that comes later, inherits the old tradition and builds onto it, and it goes on. Now, such incorrect additions or interpretations (by good or evil intent), might make some people uneasy about it. While it is usually about Fiqh, and other minor issues, the uneasiness grows bigger, until it reaches a point where some people start calling to reform; that is, "going back to Quran & Sunna" as most of the Salafis put it, and throwing the tradition away.
So they are reformers, but very strict on how they derive their rulings, thus conservative. You can easily find someone who would request you to fold up your trousers (for men) when praying, as what is below the ankle is in the hellfire as a hadith says. However, the difference of context is clear here, as it was back then a sign of arrogance, but now you can be the poorest of the poor, and you have a long trouser below the ankle.
So, they are autodidacts, but because of that, they interpret most of the things literally, leaving the context, which sometimes produces conservative opinions.
However, it is important to note that it is not a structured movement, so you might have conservative groups, and those that are not really conservatives, but differ is some other things. It is a continuum.