Nowadays most Linux users seem to use ssh user@host. When I was getting started, that didn't exist (or at least I was unaware of it) so I still frequently use the -l flag instead.
Nothing wrong with it, just that at least I mostly encounter its use by experienced users.
OIC. Good to know in case I ever have to work on some old CentOS 5 box lying around ever again.
It also looks kinda proper, using that instead of the @, so when making shell scripts, I might want to prefer this.