No. Markup was removed as the storage method in version 4, several years ago. It is still used in a handful of admin areas. But not pages.
You can still type it, and the editor will recognise it and translate, but the data is not stored as markup, so pasting it in doesn't work.
You can also insert Markdown which will be automatically converted to Confluence format (and cannot be changed back. The reference is on the page you linked to:
I checked it on the latest version of Confluence Cloud and it is still there.
If you want to keep it in Markdown format, then I would recommend you use my plugin that Robert mentioned.
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG