I agree. You have to know your lego blocks well and understand where they fit and where they don't. But if you choose to remain ignorant of the available lego blocks, and instead write everything from scratch every time, you're wasting a lot of effort.
> But if you choose to remain ignorant of the available lego blocks, and instead write everything from scratch every time, you're wasting a lot of effort.
That's a good seam upon which to filet this analogy. A quick Google search turns up uncertainty as to how many different bricks there are. It could be in the 3000s, 6800s, or over 12000. We are all ignorant of the available lego blocks.
I'm not entirely sure what you mean. But if we're talking about AWS cloud services, there are certainly AWS experts who know how to develop software in a cloud-native way and utilize most or all of the relevant services. That knowledge is what we are paid for. It's also true that there are a lot of AWS services available and expertise is divided into different specialty areas, like ML, IoT, etc. Hard to be expert at everything.
It only looks like reinventing the wheel every time if you're completely ignorant of the subtle differences of each problem domain. And if you make a bunch of changes to create arbitrary lego bricks then now everyone has to learn your brick framework before they can make an 8x2 brick.