Presumably they have unused compute in those hours and figure they may as well enable people to use it and get more invested into their ecosystem.

What I wish Anthropic would do is be a lot more explicit about what windows apply when. Surely they have the data to say "you get X usage from hours A to B, Y usage from B to C"

or see if they can shift some end user workloads to off hours so that they aren't bogging things down during peak hours.