Hellll no. The addition of grappling / submission as a way to end a fight actually makes mma much safer on the whole than boxing. Striking takes less precedence in mma and becomes more situational. Many fights are won with armbars or similar submissions, which are much, much less traumatic long-term than sustaining nothing but blows to the head in every fight. Additionally i'd argue mma referees are more conservative than boxing refs, stopping fights earlier and being quicker to prevent injury. I can't overstate how fucking brutal boxing is, how many fights i've seen where the ref takes far too long to end the fight. When you talk about people like george foreman, or even a newer boxer like gennady golovkin, these are much more powerful strikers than anyone in mma. George foreman, despite being a good person, probably gave several people brain damage throughout his career. Boxing might not look as flashily violent but it's MUCH worse for the athletes long-term.