I assume you've never conducted interviews, am I correct? There are so many "developers" out there that simply can't code, regardless of what their CV or education says. 15 years experience with Java development as a senior developer but doesn't know integers have a limited size (never heard of BigInteger), knows a hash map is used for key-value but not what hash means nor what the point of an interface is? Sure, I've seen that candidate. There's just so many terrible developers that you pretty much have to do some extra filtering to weed these out.