I'd be seriously impressed by anyone who could actually learn math or physics from wikipedia. Those articles are so poorly written and jargon heavy that I rarely learn anything from them.
Happily the computer science articles tend to make at least a little sense. But then I already have a degree in the field.
The articles are in fact extremely well written, but they are encyclopedaic. They are not written as a textbook, but as a reference work. Most articles assume you're nearly there and need the details.
There are people who can learn from encyclopedias, but most people need well-paced, linearly(ish) arranged material.
Happily the computer science articles tend to make at least a little sense. But then I already have a degree in the field.