Have you ever hit alt + backspace while in a zsh session, intending to
delete just the last part of a path, or a word, or an identifier, but ended up
deleting far more than that?
This is probably because you are using the default value for $WORDCHARS.
The default value for $WORDCHARS is
*?_-.[]~=/&;!#$%^(){}<>i.e. pretty much everything and the kitchen sink. Usually, therefore, you will want to remove characters which you don’t want to be considered parts of words