To be a contrarian, I'll go the other way on this: the demise of the 1-2-3 irons made hybrids possible!
My reasoning is that as modern iron sets became gradually more and more delofted, and the gaps at that end of the set got smaller and smaller. (The opposite was happening on the top end, thus the birth of the gap wedge.) Additionally, 7-woods replaced 3-irons for many, if not most, and 1's and 2's now carried so little loft that they were almost unusable, especially compared to vastly improved fairway woods.
All of this left room in the bag for the "utility" club, which, in most cases, carry the loft of a 3-4-5 iron, rather than a 1 or 2 iron. The majority of the golf world has never SEEN a 1 iron, never hit a 2 iron, and hasn't owned a 3 iron since the other Bush was president, so it isn't exactly accurate to say that hybrids replaced 'em.