It’s true that a lot of what we consider Orthodoxy is a reaction to Reform. Perhaps the most relevant is the exclusion of people who are not on a particular level observance-wise. Witness the difference between non-observant Ashkenazim, who most often have no connection to Orthodoxy, and non-observant Sefardim, who are perhaps less affiliated than observant Jews, but are adhering to essentially the same ideas.
