MMA fans really do have a weird ‘we would win in a street fight’ complex. It’s kinda sad to see.
Overall, MMA does equip you marginally better for a street fight, but it’s nowhere close to the fantasy situation most MMA fans seem to have, where an elite boxer crumbles at the first leg kick.
Real fights are unpredictable. Everything you see in MMA is focused on the premise of 1vs1 combat and a lot of the grappling immediately becomes significantly less threatening when that rule is removed. Boxing doesn’t - indeed it’s probably the single best form of combat for dealing with multiple opponents.
There’s also the unpredictable nature of ‘real’ fighting. What people really mean when they talk about a street fight is basically an MMA contest in the streets, which is entirely unrealistic. You don’t start 20 feet apart from one another, you don’t have a good understanding of your opponents strengths and weaknesses etc. It’s a largely unpredictable event that, in my experience at least, starts with people almost face to face with one another, and with punches being thrown. You don’t want to engage in that with any decent level boxer.