The effect is probably for the layman who doesn't usually build things, so when they finally build something (which is a human built-in dopamin effect, humans love building
things), they are attached to it.
However, when you're an engineer and build things daily, it's more of a nuisance than a joy.
Most of these types of psychological effects are disconnected from logical reasoning and work even if you are aware of them and try to account for them. For example, pricing something at $9.99 instead of $10.00. Studies have shown that when people are perfectly aware of why this is done, it still has the desired effect.
However, I do value things I've actually made more than they are really worth. It's the sense of "this is a one of a kind item made by hand; nothing exactly like it". (Even though it could be mass produced in very good quality, perhaps even better, at lower cost).
That's kind of the "IKEA effect", but I don't see how you can get it from putting together a few mass produced IKEA parts. There is just about zero room to put any "you" into it.
However, when you're an engineer and build things daily, it's more of a nuisance than a joy.