Over on BCD we've introduced spec_url:

The spec_url property is a URL or an array of URLs, each of which is for a specific part of a specification in which this feature is defined. Each URL must contain a fragment identifier (e.g. https://tc39.es/proposal-promise-allSettled/#sec-promise.allsettled).

It is populated for all javascript.* features and we're working on populating it for html.* features. At some point all BCD features will have a spec_url property.

Further, the spec_url data in BCD is carefully reviewed and we make sure it actually contains relevant specs and not abandoned or outdated ones.

Therefore, I think the "Specifications" section on MDN pages should use this information to render a specification table (or specification section as opposed to a table as recommended by @nschonni in #1121 (comment). That way we no longer need to maintain it in two places.

cc'ing @sideshowbarker with whom I worked on this a lot.