The list of options is larger than that. There are mitigations that can be quickly applied. See, e.g., https://ma.ttias.be/php-cve-2026-109618-early-mitigation/ and https://aws.amazon.com/blogs/security/using-aws-waf-to-apply...
Meanwhile, WAFs are being continuously updated with detection signatures.
Mitigations and patches are in the same category, so now you're applying mitigations without testing. What if your new WAF detection signature has false positives etc.?