Every time Web Components is being fronted, one has to duly inform the reader that Apple _rightfully_ refuses to implement what in my humble opinion is at least one broken piece of the specification that if implemented -- and it is implemented faithfully by Chrome and Firefox browsers -- in principle breaks the Liskov's Substitution Principle: * https://lists.w3.org/Archives/Public/public-webapps/2013OctD... * https://lists.w3.org/Archives/Public/public-webapps/2016JanM... To be fair, this only concerns so-called "custom elements" that need inheriting existing HTML element functionality, but the refusal is well explained IMO. Meanwhile everyone else is just chugging along, like it tends to happen on the Web (e.g. History API giving way to Navigation API that in large part was designed to supercede the former).

To all of the above I might add that without "custom elements" Web Components is severely crippled as a feature. If I want to sub-class existing functionality, say a `table` or `details`, composition is the only means to do it, which in the best style on the Web, produces a lot of extra code noone wants to read. I suppose minimisation is supposed to eliminate the need to read JavaScript code, and 99% of every website out there features absolutely unreadable slop of spaghetti code that wouldn't pass paid review in hell. With Web Components that don't implement "custom elements" (e.g. in Safari) it's a essentially an OOP science professor's toy or totem. And since professors like their OOP theory, they should indeed take Liskov's principle to heart -- meaning the spec. is botched in part.