[barbazfoo12]

The way you learn to write well is by reading.

And of course it makes a difference what you read.

Learning how to do anything well takes practice.

But you will not become a good writer unless you read.

As for what you should read,

"Garbage in, garbage out."

What do you think are the effects on your writing from reading blogs like "codinghorror"?

If your aim is to be a better written communicator in business, then you should read business correspondence from good sources.

[CeiII]

While reading helps to improve your understanding of what makes good writing, I feel writing regularly is more important. You need to learn to foster your own ideas through writing, being careful not to just think what others write.

"For ever reading, never to be read." - The Dunciad III

[barbazfoo12]

Right. But if you only ever write and rarely ever read your writing will not be as good. Reading is essential to good writing. The quote you use is encouraging the reader to write, but it also presupposes that the reader is well read ("A lumberhouse of books in every head"). Maybe that's not a coincindence.

Is there a difference in encouraging a "scholiast wit" to write versus encouraging a "dimwitted blogger"?

[CeiII]

Yes, I agree. Like all things it's a balance. In looking to refine skills everyone will require tuning in different areas. A programmer may be great at writing code but often fails to identify re-use of libraries/patterns. Reading others' code and technical articles may assist him/her in developing in that area. Likewise you may be able to tell when a writer lacks a 'lumberhouse of books'.

Being aware of why you are not developing a skill is probably key -- review from others helps to provide insight into potential underdeveloped areas.