While becoming progressively enclosed in a personal bubble is something to try to avoid, it is also important to have personal lines that are not crossed. An ad hominem attack by a piece’s author towards a commenter (or vice versa) is a line I share with you. It’s an instant “out the airlock” moment for me. It is, indeed, the modern refuge of the bully, and I won’t abide it.
I would think hard about leaving a comment regarding it on the original post. Blocking is the thematic equivalent of turning one’s back with one exception: the one being shunned has no idea you’ve done it.
I have to wonder if some entity is tracking the number of people who block a writer? If you (as a writer) reach some milestone amount of people blocking you, you get a message stating that, and have posting privileges reviewed? Likewise the people who block for no reason, just out of spite. It’s an interesting thought to mull on.
Perhaps the reason online bullying is so prevalent is because the tools to discourage it have no effect at all on the bully.