

Ah, so not the “first two” as in bullet points 1 and 2 in my list.
So, a few things here:
- Some things are covered by trademark. This can vary by jurisdiction
- Some things are covered by copyright. Also, this varies by jurisdiction
- Properly going through all the paperwork first is the safest, requires time and money, only applies in relevant jurisdictions, and requires time and effort again to enforce for only what it covers.
- Assuming the creator has the time and effort to go through 3 (if not, some stuff is arguably prior art but requires more time and money to prove), they have to be aware that anyone has created a clone of their work that would, at least in that jurisdiction, infringe.
- After they have found it, they need to contact valve and whomever else.
- If they’re not happy stopping there, then there’s the whole legal process (costing more time and money)
Edit: this is also not even the exhaustive version of the list.

I agree with this. Something like community notes on other social media might help on identification and alerting other users, but making sure that’s not gamed by bots and the like is a separate issue.