By Anush Sharma. There's a lot of good stuff in here that I'll just quote directly:
Stack fallacy is the mistaken belief that it is trivial to build the layer above yours.
Database companies believe that SaaS apps are “just a database app” — this gives them false confidence that they can easily build, compete and win in this new market.
In a surprising way, it is far easier to innovate down the stack than up the stack. The reason for this is that you are yourself a natural customer of the lower layers. Apple knew what it wanted from an ideal future microprocessor. It did not have the skills necessary to build it, but the customer needs were well understood. Technical skills can be bought/acquired, whereas it is very hard to buy a deep understanding of market needs.
Product management is the art of knowing what to build. The stack fallacy provides insights into why companies keep failing at the obvious things — things so close to their reach that they can surely build. The answer may be that the what is 100 times more important than the how.