I think that people who are scared to fight, scared to spar hard, etc. are usually the ones thinking that MMA won't work on the streets.
Not exactly.
Thats similar to the Logic that Kata wouldnt work, due to a Lack of Full Contact during Practicing them, despite perhaps Partaking in Seperate Contact Sparring, which ought be the same thing.
Or that Side Kicks dont work in Kickboxing, without realising how sheerly many Variations of the Side Kick there are, and that any Heel Kick Variation can be quite Ruthless.
MMA is highly Subjective.
Like anything, its the Person Training it.
Theres a Thread in the MMA Forum here, asking why theres less Ground Game in MMA - To which I still reply, that MMA is not BJJ with Striking.
The thing is though, is that thats exactly how SOME People Train in it.
MMA, as someone else said, is not a Magical Win Button.
Its a Sport Style, which Mixs Martial Arts to suit its Purpose.
Ultimately, its Whos Learning it.
Now, I can understand your wanting to Defend MMA - And to clarify, I think it would Work in Fighting.
But Defend with the Right Reasoning in mind.
Not just an, "If he doesnt think MMA would work, it must be because hes Scared of it."
Thats my Contribution.