hsfan,
You began this thread with asking for advice which was given, different opinions, but given, then you argue it, so why did you ask?
I did not see Grateful's advice any more than just another opinion. As we've said before, there is really no proof of what causes injury, only asumptions.
Advice for pitcher's , plan your season in advance, try to get an idea ahead. Then tailor work/rest periods accordingly.
Some say take off completely, some argue not to. It's hard when there are so many things going on. One cannot shut down completely in between showcases and camps, but there are things that can be done as suggested. I also found it confusing as we have different almost year round baseball due to our weather, up north it's different. Look at the big picture.
There is a difference in keeping one's arm conditioned and overused during the year.
You have choices. You can read about what the doctors say, what the coaches say and what the parents say and form your own conclusions.