We venerate our previous generations, and have a principle of yeridat hadorot. Therefore I would imagine that the Torah of Samaya and Avtalyon, for example, would be pure gold for us, and threaded throughout Mishna and Shas to an even larger degree than the Torah of Hillel and Shammai. Yet it is not, we have only a handful of halachot in their name.

What are the exact historical or legal reasons that this is actually not the case? For some, we haven't got a single halachic record, e.g. Mattai/Nittai of Arbela.

We venerate our previous generations, and have a principle of yeridat hadorot. Therefore I would imagine that the Torah of Samaya and Avtalyon, for example, would be pure gold for us, and threaded throughout Mishna and Shas to an even larger degree than the Torah of Hillel and Shammai. Yet it is not, we have only a handful of halachot in their name, and they hardly appear anywhere in any Talmudic-era works such as Midrash, Sifrei, Braitot and Tosefta.

What are the exact historical or legal reasons that this is actually not the case? For some, we haven't got a single halachic record or teaching, e.g. Mattai/Nittai of Arbela.

Contrast this to the point that we have, for example, a huge amount of work from Philo, who was alive at the time of Shamaya and Avtalyon, which demonstrates that the leading Rabbis of the time were writing extensively, and that it's certainly possible to have preserved such writings from that time.