When a question is voted to be closed as a duplicate, the user gets a lovely banner that tells them their question might have been asked before, and even asks them whether they want to accept the proposed duplicate or not.
When a question is voted to be closed as a custom off-topic reason, the user gets a nice comment detailing what's wrong with their question.
For the other close reason, the user gets nothing, and then their question is abruptly closed. The 5 vote system doesn't work for OP in this case, and they get zero feedback up until the very last moment.
I propose that the user would get a banner or a comment for all other close reasons as well. It makes for good UX, increases transparency and reduces surprises. Also, it increases the chance for OP to fix their question before it gets closed (Because as we know, getting a question reopened is statistically very hard, keeping it open is better).