Where do you get this assertion from that methods are post by default? Most http server implementations will reply with a 405 error for an unexpected method.
Servers that just serve static files: yes you are correct. I'm talking about application servers, proxies, etc. You need to decide to do something with a method, but all libraries, servers and clients are ready to handle them and treat unknown methods as unsafe and idempotent (like POST).
If you read my comment as 'QUERY will automatically become POST', that's not what I meant.
If you read my comment as 'QUERY will automatically become POST', that's not what I meant.