Actually, the usefulness of a document confirming education is obvious. But the skill is also very useful. After all, the employer needs a result from you, regardless of your formal education. I have seen many specialists whose hands grew out of their asses, but at the same time they had diplomas of education, certificates, and licenses...
Being skillful is going to put you into places. While in having the document of education will also give you a lot of opportunity. But I think those with skills will be able to survive whatever happens again to this world. Having formal education is going to give you a good start but having a good skill will make you stay in the longer term to whichever career you're wanting to be. Nothing wrong to have education certificates, diplomas and other formal papers to prove what you've finished but someone who's skilled will also have those opportunities given that the company is looking for such.