Do you disagree or agree that mercutio wa to blame for his own death why or why not?

Absolutely not. If Mercutio had lost in a fair fight, I would have to say he participated.... that his foolish participation and bravado cost him his life. Unfortunately, I have to blame his death on Romeo's thoughtless distraction, which left Mercutio open to Tybalt's sword. Had he been paying attention, his chances would have been about 50/50.

How could you blame his death on Romeo? Did Romeo not help intervene?

Mercutio falls to Tybalt's sword because Romeo has intervened and held him back. Romeo left Mercutio unable to fight, and thus, open to the blade of death.