Accessible? Yeah, right.

Accessible? Yeah, right.

I doubt very much data is natively stored as HTML - it's simply not a format useful for storing data in. So whether we get the data as HTML transformed from the SQL database server-side or piped via JSON and then transformed client-side, it's not the preferred means of storage; the data is already hidden behind code.

The question of native storage is not directly relevant to the issue of accessibility: HTML is principally an interchange format, and an obviously desirable property of such formats is that the data "stored" in exchanged documents can be accessed by the recipient. Similarly, JSON is an interchange format. I don't know whether Google Docs, for example, uses JSON or a similar open interchange format, but if it did not, then obviously the lack of a documented interface would be a hindrance to anyone who has issues (technical or other) with the code.

Arguably, JSON interfaces are better since you can write your own JavsScript application that runs on a page you control

Indeed. But you're referring to applications built to be interoperable, which is a step up from "black box" applications who ask your browser to run code on their behalf. Another factor is what kind of data the JSON interfaces expose. If you're only getting small fragments of the larger whole, building up an entire document is likely to be very awkward.

I have personally had to migrate e-mail data out of a Web-only system where POP and IMAP support was not available. In the end, I had to write a script to pull out each message one at a time, and I had to settle for an inferior version of the original content. I've also used another Web-based system where I was fortunately able to use POP - "fortunately" because the Web interface was very heavy on the JavaScript, and automating the Web browser and then traversing the browser's DOM would have been necessary to access the content. Moreover, that application's JavaScript didn't always work on various browsers that were normally adequate for browsing the Web - another reason for wanting to improve the JavaScript employed by that application.

Sometimes I think that people who apparently don't see the need for the kind of interoperability advocated in this matter - summarised as "I can't see why you'd want this" - have either been fortunate enough never to experience data access or migration issues, or didn't really care when a chunk of their personal data went away once upon a time.