I would like to better understand why certain tractates of mishna which don't have gemara were selected or not for inclusion in Talmud Bavli and/or daf yomi?
Here is what I understand
- most tractates in seder Zeraim and Taharot don't have gemara and are not included in Talmud Bavli or daf yomi, Berachot and Niddah are the exceptions (see this MY question)
- Shekalim has gemara in Talmud Yerushalmi but not in Talmud Bavli. Its Talmud Yerushalmi version is included in Talmud Bavli. Answers here suggests this might be to help learn the entire seder Moed since it is the only tractate missing
- Kinnim and Middot don't have gemara in the Bavli or Yerushalmi but their Mishna version is nevertheless included in the daf yomi cycle and printed in many (all?) editions of the gemara. The answer above and Wikipedia (for Kinnim) suggest this might be to help learn the entire seder Kodashim since they are the only tractate missing
- Eduyot and Pirkei Avot are not included in Talmud Bavli or daf yomi. If they were, they would enable to complete the entire seder Nezikin
So why are Pirkei Avot and Eduyot not included in Talmud Bavli and/or daf yomi as part of Seder Nezikin?