Bruce Lee believed in cross training arts long before mma was ever around.
He respected elite boxers, even trained and garnered respect from them. Trained with Gene lebell, trained in wrestling and other martial arts.
He was a pioneer in his martial arts philosophies and ahead of his time in many ways.
anyone who doesn't respect that is just clueless, probably not even a martial artist themselves and needs to shut the fuck up.
would Lee be able to come in and compete with elite fighters today? Probably not, although he was deadly. There are more than a few traditional martial artists nowhere near his level who have had success in their transition.
If he came up in this era, who knows what he could have accomplished. he was a master and would have had likely the most interesting and thoughtful mind in mma history. Those types always make fascinating, creative and cerebral fighters.
Though I think Lee's role was as a teacher and philosopher above all else. would've made a phenomenal trainer