Is there any downside in just blocking the whole META IP range? I mean they aren't even running a search engine AFAIK. Why would I want them to crawl my website?
The only downside I can think of is that links to your website that are shared on Facebook / WhatsApp / Messenger won't be able to show a rich preview because they won't be able to access the OpenGraph tags on the shared page.
Rich previews are known to cause higher clickthroughs than non-rich previews (if you care about that).
Rich previews are known to cause higher clickthroughs than non-rich previews (if you care about that).