I think anon was talking more about how things are rather than how they should be. Sure, in an ideal world people won't anonymously insult* you. However, that is not the world we live in, and demanding they stop is only going to egg them on. If it bothers you that much, then turning off anonymous comments is really the best option. Again, it'd be lovely if no one had to worry about that in the first place, but reality does not work that way, unfortunately.
*Assuming for a moment that is indeed what's happening. To many Tumblrinas seem to think insults and harassment are the same thing as disagreement and criticism. But I digress