Tom,
In J2Commerce 6 the decision to create a more standardized confirmation page with the ability to customize it per project was implemented. The two impages you attached show a non-logged in user attempting to view the order confirmation page and the other image is the order confirmation page after a sale (or if the shopper revisited the link while logged in). Since there is customer specific information on the confirmation page, there needed to be a way to block malicious actors from simply plugging in an order id in the url attempting to access that information.
As far as the article's - I will open an internal issue on that to see what is needed in order to continue to display the contents of the article in the confirmation page so you get the best of both worlds.
On a side note: the benefit to having a set confirmation page (which every other major ecommerce platform in the world provides) is that additional 3rd party plugins such as After Sale Specials and After Sale Surveys (https://www.j2commerce.com/extensions/apps/after-sale-specials and https://www.j2commerce.com/extensions/apps/after-sale-surveys) can be implemented to increase average order amounts or obtain additional information that you wouldn't normally be able to obtain easily.
Hope this helps answer the question,
Adam