It obviously didn't help her. Strange that she can't form a good paragraph, stretches ideas out across sentences, misuses semicolons, constructs sentence fragments, and avoids using beautiful language.
1. Practicing writing 140 character messages makes you better at writing 140 character messages. It's a point of faith that this skill will transfer to longer works.
2. A better title would be "Twitter as a framework for practice". What you'll find is that people who strive to get better, do so in any medium that allows it. People who don't, will fail to do so in any medium.
3. In code, this is called 'golf'. It's generally thought to a pleasant-but-useless practice (I assert). Why would this not also be true in this context?
1. Learning to express oneself concisely (while still conforming to rules of grammar) as well as verbosely may make one a better writer.
2. Writing tweets does not necessarily help one learn to express oneself concisely. For many, it leads to dropped articles, lack of punctuation, and other issues that may reduce the expressiveness of the prose.
However, kudos to her for coming up with a headline that attracts attention and page views.
Copyblogger is a waste.