Comment by ssl-3
There's a wealth of easy projects that a person can get started with using an Arduino.
Without any opportunities for getting bogged down in anything extra at all, they can follow a simple recipe and quickly begin to blink an LED at the rate of their choosing.
The Arduino was developed to be a teaching tool, and it allows for a person to take little baby steps.
(Whether this placement is good or bad for Arduino as a business entity isn't something that I find particularly important.)
Blinking an LED is what you do for "hello world" on every microcontroller board I've tried. The Arduino IDE supports boards from many different manufacturers.