It has capability to e-mail the committers, but on hydra.nixos.org that’s unused for years, as it (reportedly) generated too many messages in practice.
One issue is the huge influx of commits, so you diff only large amounts of them at a time and thus you (need to) send a message to all of them with the whole list of regressions.
… and there was a situation when the situation from the second quote lead to the first one. It was something with branch setup, and Hydra ended up sending hundreds of email (per person) to a large fraction of active maintainers.
Naturally, this was found an unacceptable failure mode. Nobody since have proposed patches that would even claim to protect from this failure mode well enough that reenabling the emails could be discussed.