As a developer you will always use tools and rely on applications others have written. If you write your program in C, then you use a C compiler like gcc and most developers have not read the whole source code of gcc. Same is true for the C library you use, including standard library, you rely on others developers code you have never seen.

Therefore, I think the IKEA effect holds true in software development, because you rely on "pre-assembled" items, but I agree that you have much larger degree or freedom on how you build your application in e.g. C compared to a IKEA build. Maybe, this higher degree of freedom even strengthens the effect.