Everyone who changes their conventional oil at 3K has not been subject to a lobotomy.
For one, it is safe and will keep your engine clean better than any other technique.
Two, some driving and climate conditions require this or even more frequent OCIs.
Three, some engines are beat up or have a faulty design that would benefit from the 'old school' 3k changes.
Sure, engines and oils are getting much better in this respect -no doubt.
I agree that changing a full synthetic at 3k is bit early , if you are near anywhere normal conditions.