I think it is mostly because of all of the crap we’re encouraged to buy and put on our face. A ridiculous number of products put certain types of fragrances and oils (some oils are good, don’t hang me) and other unnecessary but irritating ingredients into products that honestly don’t need them. I had to learn the hard way to purge and start over with very gentle, fragrance-free everything. When I started using something like Differin, I used Dr. Dray’s method of application by easing into use, applying it once every couple of nights, not immediately putting it on every single night as the instructions say to do. Applying it nightly right off causes irritation which would discourage most users.
Also, we expect immediate results. I know a lot of people who will try something for a week and complain that it isn’t doing anything for their acne. In my case, it took me at least 2 months before I had consistent results using Differin and later adding BP (like an Epidou dupe). Skin has a turn over cycle. Things like Differin will increase turnover — at times making acne seem worse before it gets better because everything is coming to the surface at once. After 2–3 months, you should start to see improvement in your complexion. But even now, I don’t use it every night. The moment my sensitive skin shows any signs that I’m starting to overdo it with the Differin, I take a night off and just wash and put a little low-% vit c serum (from the ordinary) on and call it a night.