The posts by tennisballa and arche3 really nailed it out of the park. I have been coaching for 20 plus years and have lots of coaching buddies much smarter than I am, but who do not post here.
The reasons are all the same. A few very prolific posters will dissect every post. They will use physics and/or obscure logic to twist and muddy any basic instruction that is given.
By the end of the thread everyone's head is spinning and even the most fundamental instruction tips are lost. I could not imagine being a tennis newbie here....trying to pick out the good tips that would actually help them, from all the confusing noise, would be impossible.
If LeBron James had his every movement analyzed by these posters, and tried to muddle through and follow all their analytical advice, the poor guy would be so confused he would not be able to walk and chew gum anymore.