I like to bring up the English language in this particular debate. "It", "he", and "she" are incredibly non-descriptive names, but each one of them is used many orders of magnitude more often than any "descriptive" name (other than maybe "I" or "you") and yet we don't hear rants about that.

The reason is exactly what the original commenter pointed out - scope. Sometimes the word "it" is descriptive enough all by itself. Other times it isn't. It's a more subtle matter than "worst variable names".