I mean, it sounds more like "The messier your project, the more difficult the unit testing". What you're describing sounds like issues with SRP and LoD. Which will inevitably happen as big projects get rushed, but let's place the blame where it belongs: rushing.

Yes unit tests take longer up front, but for projects that you need to update and maintain for a long time, they're a huge boon.

You can't do everything with a unit test obviously.