Jeremy Keith is wringing his hands about Web Components. I likewise can't attend the second Extensible Web Summit and so have a bit of time to respond here.
Full disclosure: I helped design Web Components and, with Dimitri Glazkov and Alex Komoroske, helped lead the team at Google that brought them from concept to reality. I am, as they say, invested.
Jeremy's argument, if I can paraphrase, is that people will build Web Components and this might be bad. He says:
Web developers could ensure that their Web Components are accessible, using appropriate ARIA properties.
But I fear that Sturgeon’s Law is going to dominate Web Components. The comparison that’s often cited for Web Components is the creation of jQuery plug-ins. And let’s face it, 90% of jQuery plug-ins are crap.
Piffle and tosh.
90% of JQuery plugins don't account for 90% of the use of JQuery plugins. The distribution of popularity is as top-heavy there as it is in the rest of the JS UI library landscape in which developers have agency to choose components on quality/price/etc. The implicit argument seems willfully ignorant of the recent history of JS libraries wherein successful libraries receive investment and scrutiny, raising their quality level. Indeed, the JS library world is a towering example of investment creating better results: the winners are near-universally compatible with progressive enhancement, a11y, and i18n. If there's any lesson to be learned it should be that time and money can improve outcomes when focused on important libraries. Doing general good, then, comes down to aiming specific critique and investment at specific code. A corollary is that identifying which bits will have the most influence in raising the average is valuable.
Web Components do this cycle a solid: because they are declarative by default we don't need to rely on long-delayed developer surveys to understand what is in wide use. Crawlers and browsers that encounter custom elements can help inform our community about what's most popular. This will allow better and more timely targeting of investment and scrutiny.
This is worlds different than browser feature development where what's done is done and can scarcely change.
A particularly poor analogy is deployed in the argument that Web Components are somehow a rehash of Apple's introduction of
<meta name="viewport" value="...">. This invokes magical behavior in some browsers. We're meant to believe that this is a cautionary tale for an ecosystem of intentionally included component definitions which cannot introduce magic and which are not bound by a closed vocabulary that is defacto exclusive and competitive -- other browsers couldn't easily support the same incantation and provide different behavior without incurring developer wrath. The difference in power and incentives for browser vendors and library authors ought to make the reader squirm, but the details of the argument render it entirely limp. There is no reasonable comparison to be drawn.
This isn't to ignore the punchline, which is that copy/paste is a powerful way of propagating (potentially maladaptive) snippets of content through the web. Initial quality of exemplars does matter, but as discussed previously, ignoring the effects that compound over time leads to a poor analysis.
Luckily we've been thinking very hard about this at Google and have invested heavily in Polymer and high-quality Material Design components that are, as I write this, undergoing review and enhancement for accessibility. One hopes this will ease Jeremy's troubled mind. Seeding the world with a high-quality, opinionated framework is something that's not only happening, it's something we've spent years on in an effort to provide one set of exemplars that others can be judged against.
Overall, the concerns expressed in the piece are vague, but they ought not be. The economics of the new situation that Web Components introduce are (intentionally) tilted in a direction that provides ability for cream to rise to the top -- and for the community to quickly judge if it smells off and do something about it.
Yes, messes will be made. But that's also the status quo. We get by. The ecosystem sets the incentives and individuals can adapt or not; the outcomes are predictable. What matters from here is that we take the opportunity to apply Jeremy's finely-tuned sense of taste and focus it on specific outcomes, not the entire distribution of possible outcomes. It's the only way to make progress real.
PS: Extensibility and the Manifesto aren't about about Web Components per sae. Yes, we extracted these principals from the approach our team took towards building Web Components and the associated technologies, but it cuts much, much deeper. It's about asking "how do these bits join up?" when you see related imperative and declarative forms in the platform. When there's only declarative and not imperative, extensibility begs the question "how does that thing work? how would we implement it from user-space?". Web Components do this for HTML. Service Workers do this for network caching and AppCache. Web Audio is starting to embody this for playing sound in the platform. There's much more to do in nearly every area. We must demand the whole shebang be explained in JS or low-level APIs (yes, I AM looking at you, CSS).