Yes, logs are important for running the service. You were supposed to realize when you said that, that “is this useful” is a factor in how long you keep logs, alongside “how much does it cost”.

I do work at big tech and see a lot of logging policies, in fact. Having lawyers involved doesn’t make it “no legal considerations”, it makes it properly assessed legal considerations. It is default practice across big tech (and other large professional industries) to delete eg email as soon as reasonable in order to reduce discoverable records. It is also required for most services that they be able to delete logs and archived material to comply with the laws about keeping personal data around for no purpose - most places will never see this brought up but if they do, it can be a big deal.