the pali cannon does name three boddhisattvas, so the idea of boddhisattvas isn't just mahayanna. they were tara chenrezig and i forget the third, maybe manjushri. however the whole idea of buddha nature is hard to find in the pali cannon. there are afew phrases that are tortured to support the idea. once you have the oidea of boddhisattvas then there is no bar to more. moreover once you accept the idea of enlightenment then any enlightened teacher can teach new things. buddhism is specifically not a religion based on fixed doctrine like the western religions. moreover the split was as much about therevadans accepting the political and military support of the ashokan dynasty which in the eyes of others, including the other 12 southern pali cannon schools) as violating renunciation. now of course the leaders of most of tibetan buddhims and most vajryanna are not renunciates. they are hoarding wealth and power, this is the real source of the problem. many chinese mahayannists have renunciates in charge and operate democratically internally. the p[roblem with vajrayanna is the lack of renunciates breeds corruption, which is exactly why buddha wanted all buddhists to be renunciates and considered non renunciate buddha followers to be friends of buddhism and not buddhists. that's the official position in the therec=vadan societies today.|
hence the real issue isn't the boddhisattva practices or the theories of bodeies, all acceptable to you if you think they were taught by an enlightened person, but the lack of renunciates. that breeds corruption. there are crazy sub sects like the trungpa stream(which gets weirder and more disgusting the more i read about it--especially trungpas having sex with girls under the age of consent in canada where at the time the age of consent for a person in a position of authority was 21, he committed many sex crimes) but you can have a healthy vajrayanna group, or mahayanna group, unfortunately most are not.
hence the real issue isn't the boddhisattva practices or the theories of bodeies, all acceptable to you if you think they were taught by an enlightened person, but the lack of renunciates. that breeds corruption. there are crazy sub sects like the trungpa stream(which gets weirder and more disgusting the more i read about it--especially trungpas having sex with girls under the age of consent in canada where at the time the age of consent for a person in a position of authority was 21, he committed many sex crimes) but you can have a healthy vajrayanna group, or mahayanna group, unfortunately most are not.