That comment would make more sense if that were true for ALL toolbar items, which of course it isn't.
Why is it not considered 'confusing' to users to hide/show toolbar items at their discretion, yet it is considered to be 'confusing' to users to hide/show the TOOL/SIGN/COMMENT buttons?
I don't understand Adobe's logic in not just allowing those buttons to be individually hidden like every other button on the toolbar?