The main element was designed and implemented based on the concept of there being a single instance within a document, the markup pattern was based on data of id value usage in the wild. The whatwg definition differs markedly from the orginal definition. This leads to confusion for developers.
The W3C nu html checker, which is used by many, throws an error when main is used as per whatwg. Data derived from webdevdata.org shows that >97% of usage of the <main> element is as per the W3C definition and anecdata from users that consume the semantics suggests that one main element per page is the expected and most useful pattern. In general consumers landmark semantics report that the utility of landmarks is reduced as the number/instances of landmark elements in a document increases.
The alignment would involve changes to the main and body element definitions.
current W3C definitions:

• main element
• body element