Most likely if you run up to some thugs wanting to cause
trouble, they'll make sure they outnumber you... so some idea of
how to handle multiple opponents is quite useful.
Can't say much for styles I don't know much about, but I was
wondering how useful BJJ was in a multiple opponent situtation- I
mean you can't exactly ground fight with one guy if there are two
other guys grabbing at you rite? Stand up fighting would be more
pratical for keeping multiple opponents at bay.
On the other hand, a person who only knows stand up with no clue on
what to do while on the ground would find his fight over the moment
he hits the ground.
What I am saying is, I think before we bash other styles we might
as well learn what is good about them and adapt them to our own
styles. After all as Bruce Lee said, after crossing a river you do
not carry the boat with you. There was a time in MMA when grappling
and ground fighting styles were favoured (during the BJJ era) until
some stand up fighter figured how to win upsets against champions
of that style.
Once again it shows the limitations of limiting yourself to one
style and not being innovative and cross-training in others.