The Buddha is saying in the Simile of Herbs that all along – even as he was teaching appropriate to Sravakas, Pratyekabuddhas, and Bodhisattvas – he was in essence teaching in a way that was preparing for the Lotus Sutra. These initial teachings are all part of the Lotus Sutra. That is why it is important that people not come to a conclusion that the Lotus Sutra replaces or does away with the previous teachings of the Buddha. We have to think of the teachings as being on a continuum that is leading to the ultimate truth revealed by the Buddha in the Lotus Sutra.
The Buddha all along was teaching the same Dharma but he did so according to the capacity of the people he was teaching.Lecture on the Lotus Sutra