It is easy to get started with Lego, and fun to use. Those who are really good can build some impressive objects. The limitations of the parts make it easy to find challenges to overcome.

Mechanical engineering is a lot harder, there are so many options to consider, new options come along all the time so you're always falling behind, and cost plays a much larger and - I think - more boring role in the process.

I think that is analogous to the point you are making with computers.