I’d think it would as simple as a “3 strikes and you’re out!” policy. Warn them the first time, no punishment, they do it again, warn them again but prevent uploads for 24hrs on that account, and 3rd time…
No.
Feel free to add the “advertisement” tag if you’d like to those images, but as byte has stated - we have a complex tagging system with over 100,000 tags in existence. Unless it appears that someone is intentionally and maliciously leaving tags off images to avoid filters, we don’t ban people for missing a tag or two.
Also, TBH, I’m more in favor of getting rid of the “advertisement” tag anyway - it causes some issues with ad blockers falsely blocking images.