Pointing out the posts I made 2 years ago when I was a "newbies" is pointless. It's just a blackmail
Rule was existing 2 year back also. If you are not caught at that time it does not make you innocent.
Think if you were banned as newbie then you have nothing to show that you have any "net positive" to the forum.
It is not the blackmail but you can ask for forgiveness.
Is posting relevant articles from external sites with reference URLs against the forum rules? Yes or no?
It is low quality post and forum rules prohibits you to do so. Forum want yours words and discussion and we are not looking for a post that is copied with reference link. If you having nothing to add and discuss on that external site article then you should not post them. (though adding link will not get you banned.)
You can use external site link if it is relevant to your original answer, give some facts to your answer or increase the weight of your answer.