One follow up question:
#3
They were convinced that Dhamma required new re-formulations to meet the needs of new ages, new populations, and new social circumstances. So they set out to produce new literature, which ultimately came to be known as Mahāyāna Buddhism.
#4
Within those heydays of Mahāyāna Buddhism, it corrupted Theravāda Buddhism in Sri Lanka and other Asian countries.
These actions by early Mahayanists would be anantariya kamma, wouldn’t they? Creating schism in the Sangha.