That's a POSIX standard feature:
https://pubs.opengroup.org/onlinepubs/009696799/basedefs/xbd...
The argument -- should be accepted as a delimiter indicating the end of options. Any following arguments should be treated as operands, even if they begin with the '-' character. The -- argument should not be used as an option or as an operand.
Learning and understanding the bash oddities is key for me because I use it so often. It's the same reason I quote every expansion; sure my text likely doesn't have spaces, but maybe it does and id rather use the extra quote characters to ensure I don't have to troubleshoot language grammar bugs in my code