This is a nonsensical comparison. If you were truly "angel investing" in your employees, you would be there at birth handing out shares. Or maybe "series A" would be recruiting them at their high school graduation.
All I'm saying is that if, as a business, you are seeking to minimize your risk portfolio during hiring you are, by definition, not seeking to hire the "best" employees, but to hire the best employees with the lowest risk profile.
Once again, I don't think this is bad. You're running a business and the task is to get the highest probability you'll hire a productive employee.
Nonetheless, the OP has a point that you may lose employees due to your risk tolerance being too low.
Example: I work on the C# compiler. I'm not going to take a prospective employer's "knowledge test" on C#, regardless of if that is statistically a good filter for them in hiring.