It is what Web Components were supposed to be, but they're not living up to that yet. They're reliant on client-side JavaScript, have special needs that cause them not to be well-integrated in the most widely-used JS framework yet, and have a number of other issues - as evidenced by the fact that there's still not a custom element that basically solves the mentioned limitations of Data Lists and is widely used and can be counted on to be as well-done as native elements in areas like accessibility.

I partially blame those who were trying to repurpose them as an application architecture framework, but primarily it's just a hard problem to solve.

Which is fine, but it's a shame that at the same time there's been practically no progress on the actually built-in elements, especially when you compare it to e.g. the amount of progress that's been made in JavaScript.

I'm probably ignorant: is there an example of any kind of custom element, in 2012 or now, with customization (nevermind CSS styling) that does not depend on JavaScript?

No, that's one of their limitations. (Well, styling can be done to some extent with CSS variables and the shadow DOM, I think.)

Ok, so as someone new-ish to web programming, how should I understand the current relevance of 2012's Extensible Web Manifesto, and the dissatisfaction you're expressing about <datalist> and about Web Components?

I'm sure it's due to a failure of imagination, maybe my own or maybe more widespread, but I don't actually know what you'd rather have, since it seems that there is still no concrete (even experimental) prototypes for kind of custom elements that you're envisioning. What am I missing?

So I'd prefer either:

- built-in elements that cover common elements like autocompletes or typeahead elements that allow e.g. the inclusion of images and formatting with their suggestions, or

- custom elements to work well enough in practice that those elements would have been created by third parties and would be widely used now.

I don't know whether the latter is actually possible, but I'm lamenting the fact that a focus on that goal seems to have coincided with hardly any attention being given to the former.