Nor am I obligated to use systems and services which don't support minimal HTML interfaces. Graceful degradation is generally useful, particularly as most web spidering is still basic HTML (some now support aspects of JS as I understand). You're invisible to the world if you can't get indexed.

I've also found that the very rudimentary browsers included in cheap feature phones tend not to work particularly well with any measure of "modern" websites (though others do support these fairly well). While I don't suppose these are a large financial market, they're likely a large user market, as those phones are both cheap and exceptionally thrifty with battery life (weeks, not hours).

Given that this is graphical content, that's less a concern. But as I noted above: simply providing a fallback JPEG alt would have worked.

And noting an issue isn't the same as complaining. Actually, if you'll note, I fixed the problem, after a fashion, by providing a link to alternate and accessible content.

But thanks for your depth of understanding, empathy, and sympathy.