Cute input redirection: bash vs. zsh

I ran into this answering a StackOverflow question about the best way to append 1 file to another.

This method seemed cute, though I doubt I’d ever use something that hard to read:

>> a < b

The < dumps the contents of b to STDIN, and the >> should append STDIN to a, effectively appending b to a.

In bash, this doesn’t seem to work. But in zsh, it does.