That can be counter productive as stalkers sometimes interpret it as a sign that they are getting to you. I had an obsessive ex who, after I blocked her on WhatsApp, started texting instead and then when I blocked her number altogether, she just went and bought another phone. In the end I just ignored her and she went away, although 6 years later I still occasionally get messages from her, usually at Xmas and on my birthday etc. It’s actually my birthday today, so let’s see…..