I wouldn't say afraid but don't see the reason. Vast Majority of Developers are working where repo = single application and their git workflow is Scaled Trunk Based: https://trunkbaseddevelopment.com/#scaled-trunk-based-develo... main, branch, work, merge, repeat and they almost always fix forward.

Also, Rebasing is cause for Dev Riots because of nightmare merge conflicts that can result.

Since the author is from Google, my guess is they are seeing issues that hit the level of "WE MUST FIX THIS" that only arise at Google Monorepo size.