Cosmetic question about usage of grep

[realsimix]

Hi,

While working with acme.sh I started wondering about the grep usage, like grep -- "$BEGIN_CERT" "$_certf"

I never saw using -- mentioned anywhere in a grep man page, be it on Unix or Linux (GNU) or pure POSIX grep.

I see that it works and understand what it is asking to do, but would it not be better to use -e instead?
So above example would look like

grep -e "$BEGIN_CERT" "$_certf"

Don't get me wrong, I'm just asking because I always used grep -e ... instead.

Thanks,
Simon