I think it's just because that's their "app" login page, where you already know what it does and you already have an account. When I go to login to AWS or Datadog or whatever, the login page doesn't tell me what it does, either.

Like you, though, I've also had "personal CRM" as a potential project for a very long time. Monica is a great step in that direction, and I've happily used it for many years, but it's not all the way there, and I still hope to one day have the resources and time to actually build something truly great.