You are free to do that, but restricting blood flow that much is not healthy.
How is my blood flow restricted in any way by a watch band? Believe me, I think I would be the first one to notice if I was restricting blood flow, that is the most ridiculous thing I have ever heard!
Additionally, I really think you are being extremely judgmental from one picture that probably actually misrepresents the watch as looking a lot tighter than it really is. If I rotate my wrist around the watch moves! Believe me, your insulting "concern" is not wanted nor warranted. Good day.