Why do some countries cheat in the Olympics? Because it is no longer a contest of human achievement, it's just about the medals as a symbol of national glory. Of course: once all countries are doping, the medals will become meaningless. College degrees will suffer the same fate if everyone cheats to get them.
Testing doesn’t work for everything, especially for dissertations, publications, research etc. That being said I’m wholeheartedly in favor of using extensive in class testing when applicable.
Diversity in evaluation methodology is a reliable way for many subject. Even short, minimal handwritten exams would help to assess student understanding at a few key checkpoints and should should be reintroduced.