Sure, but when the standard says "read this file and execute the instructions you find at the beginning" that is more dangerous than "this is a file with data and your program needs to figure out how to read it".
Ok if you want to be pedantic, the standard says, "if you can't read this file, go to the offset and then execute the code you find" which isn't functionally different from what I said.
The WASM encoders/decoders are embedded resources that exist as byte offsets in the file metadata, not header info.