could i just load the blink sketch on its own on say a uno or mega ?
If you are a hobbyist, and you don't want to buy a programmer and you want to save the trouble of configuring and learning to use the programmer... The bootloader is a beautiful thing!!!!.I've used some other microcontrollers & microprocessors in the past, and I was amazed that I could install the IDE and get the "Blink LED" example running in 5 minutes! With a lot of other platforms, that process could have taken a whole day. With the Aruino being it's own self-programmer and is it's own development board, and you've saved a ton of time and money compared to starting from scratch.