Custom methods won’t have the benefit of being dealt with as if they shared specific semantics, such as being treated as safe methods or idempotent, but ultimately that’s just an expected trait that anyone can work with.
In the end, specifying a new standard HTTP method like QUERY extends some very specific assurances regarding semantics, such as whether frameworks should enforce CRSF tokens based on whether a QUERY has the semantics of a safe method or not.
What about proxies and the like? It might be less relevant in a world where most communication happens under TLS.
Custom methods won’t have the benefit of being dealt with as if they shared specific semantics, such as being treated as safe methods or idempotent, but ultimately that’s just an expected trait that anyone can work with.
In the end, specifying a new standard HTTP method like QUERY extends some very specific assurances regarding semantics, such as whether frameworks should enforce CRSF tokens based on whether a QUERY has the semantics of a safe method or not.