Thank you very much for the play-by-play. This slide deck is from 2015, so I'm willing to give the author the benefit of the doubt, that things have probably changed a lot since then.

It seems that the ZFS story has gotten much better since 2015 (FreeBSD & Ubuntu support, memory usage improvements, license problem proving to be not a big problem).

Correspondingly, it seems that the btrfs story has regressed (redhat drops support, many issues in this greater thread raised around reliability and use cases, suspect development practices).

My guess is that they were closer to parity in 2015. This deck was making the case for why btrfs would win out. The author seemingly turned out to be wrong, as we're all liable to be from time to time.

My guess is that the licensing might be an issue for some big corporations today, but it appears to be generally benign, like you say.

Thank you so much for the information! :)