Do you have any particular cases in mind where Docusign mounted a spirited defense in court despite not being one of the parties? How did those cases turn out?

At least their terms of service don't suggest any kind of general legal indemnification of customers, only a limited one around loss of confidentiality caused by security breaches in their systems.

What makes you think Google won't show up in court? They do kinda neglect their free end users, but go to great lengths to appease enterprise clients (see: Google Cloud Platform)