I found that this often applies to software developers. As someone who writes the code and understands the product internally, you lose the ability to relate to

I found that this often applies to software developers. As someone who writes the code and understands the product internally, you lose the ability to relate to the end-user. You just don't see things the way end-user sees them. This is the reason having a non-technical co-founder on board is useful -- their mind is uncorrupted by the knowledge of internals.