Comment by nip

Absolutely not insulting! In fact an excellent question!

Preview was an inspiration when I started SimplePDF, my goal was to make the "Preview" of the web, so that people without a Mac would benefit from a software matching Preview in ease of use and overall polish.

Adobe Acrobat: SimplePDF has "Simple" in the name as the philosophy is to keep it simple (both in ease of use, and features): I don't intend to support everything that Adobe Acrobat does. There's a lot of features that I could build that I intentionally do not, as they would bloat the UI and hard the overall usability. Most people have very simple needs and don't need advanced features (like scripting, etc).