Every so often, I see this statement appear when an 'obvious' solution to a problem is discovered and the commentator wonders, in disbelief, why no-one did it ages ago. Or, as justification for why something /shouldn't/ be done, they ask "if it was so easy, why hasn't !BigCorp done it?", thereby implying there is something bad about the solution that we just don't know yet.
I think the response to both of these situations comes from considering the search space involved. By analogy, if the "answer" is a series of steps, then it can be represented as the path through a graph of possible states from the current state of the world to the desired state. To see why an 'obvious' solution is anything but, you merely have to consider the fan-out, or degree, of the nodes in the search space.
To actually find the solution may involve either a very long brute-force search, or a clever search algorithm. Seeing that a solution is "obvious" is merely saying that is easy to verify the solution is correct. This does not mean it was easy to find.
It's confusing the analogy a bit, but for examples of 'spaces' with this property you need only look at one of the many NP-complete problems.
This discussion reminds me of Contact (the book)#Adaptation). In it the instructions received describe a set of operations to perform which are simple in themselves but which combine to produce a powerful, useful artifact. It does make you wonder if we are surrounded by a sea of possible fantastic devices, which we could magic into existence if only we knew the right steps. Then again, maybe we've found all the easy wins and everything left will be a struggle. Here's hoping not.