The worst is when you ask something that is subtly different enough that it really isn't the same question anymore, and then they shut you down anyway. Perhaps to somebody with expert-level knowledge, it might be the same, but for someone trying to learn something new, subtle differences can be huge.

The yellow box above the question does give a link to the previous answer. Is that what you're talking about?

EDIT: also, more annoying is-

"I want to do this. How do it do it?"

"No, don't do that. Do this other thing instead."

Why is that more annoying? Do you really expect people to give out what they themselves believe to be bad advice, and is so, is that really desirable?

It's preferable to just ignore the question; or to ask in comments if alternative solutions are wanted.

To be fair to Stack Exchange, that's a behavior that's been around forever; at least since USENET. It is very annoying, though.

"How do I do this?"

"USE THE SEARCH, NOOB"

(Search results contain dozens of people asking the same question; not a single answer; and then someone saying "never mind, fixed it" with nothing about what they did to fix it)

Good news - it's literally right there at the top of the question. "This question already has an answer here:" with a link. It is impossible to close a question on SE sites as a duplicate without providing the question being duplicated, for this very reason.

It irritates me when they flag the question as duplicate and not provide a link to the possible original and it's incredibly hard to find a similar question. It wud be just easier to link the original instead of all the traffic coming from google finding a dead end.

It's impossible to do that on SE sites - if you try to flag as a duplicate, the site requires you to chose the question you believe the one you are flagging to be a duplicate of. The ability to vote is disabled until you do, and the site then shows the link in a comment and eventually at the top of the post if it gets closed.