That is not correct. It says it is valid for version 27 and up. In every version since, the preferences file come with the option Enable MSE for WebM video default marked active.the preferences help file wrote:Enable MSE for WebM video: This enables the use of MSE for media in the WebM video format.
This is disabled by default because it causes issues with seeking and looping of media in the player implementations on the main websites where this combination is used.
Besides, the help file says nothing about Enable WebAssembly (WASM), on the same page in the prefs.