Full automation is not at all folly. Manual testing doesn't scale and can't practically be done on large, complex products if you want to release on a rapid cadence while keeping costs reasonable.
The only two types of testing you can't really automate are exploratory testing and usability (UX). Exploratory testing should be done concurrent with product coding, and then the tests that seem useful can be scripted as a permanent part of the test automation suite. Usability testing should be done either on a separate branch, or on the release branch with a feature toggle. It's essentially part of requirements analysis and not part of qualifying a particular build for release to customers.
While Scrum doesn't call for any particular testing approach, in practice it's almost impossible to do Scrum effectively on a large product with multiple agile teams unless you have a very high level of automation. Otherwise development just bogs down and you end up with nonsense like "hardening sprints" (basically waterfall in disguise).
The only two types of testing you can't really automate are exploratory testing and usability (UX). Exploratory testing should be done concurrent with product coding, and then the tests that seem useful can be scripted as a permanent part of the test automation suite. Usability testing should be done either on a separate branch, or on the release branch with a feature toggle. It's essentially part of requirements analysis and not part of qualifying a particular build for release to customers.
While Scrum doesn't call for any particular testing approach, in practice it's almost impossible to do Scrum effectively on a large product with multiple agile teams unless you have a very high level of automation. Otherwise development just bogs down and you end up with nonsense like "hardening sprints" (basically waterfall in disguise).