Good gosh. Reading has EVERYTHING to do with writing, in my opinion.
It has been my experience that people who read a great deal have better writing skills than those who don’t.
There are always exceptions both ways to this rule of thumb, but if one reads extensively, the patterns of grammar and syntax are embedded in the brain and can be implemented anytime something has to be written.
"The man who does not read good books has no advantage over the man who cannot read." -Mark Twain