Look at any hobby and there are lots of beginners and casuals and far fewer people who are very skilled at it. The Maker hobby is no different. It's certainly not a problem of the microcontrollers available. Arduino is the simplest, but there are plenty of others.
The "blinky LED" roadblock is really just a result of the fact that more complex "maker" projects require some amount of electrical or engineering or fabrication knowledge and skill, which takes some trial and error and practice -- the same thing that limits progress in lots of other hobbies.
The real "Maker" movement is the demand that drives so many consumer level fabrication tools and components that were only available as expensive industrial and commercial orders in the past -- 3d printers, laser cutters, microcontrollers, IC sensors, brushless motors -- there are so many options now that just weren't available at all 20 years ago.