[Artemix]

Isn't it obvious? For which reason, if not tracking and information gathering, would such a feature even exist?

Best solution is still to block Facebook's infrastructures, as always.

[xstartup]

I disagree, it's not at all obvious. Pixels are used for conversion tracking (cookie pixels/cookieless pixels). Crawl isn't necessary for a pixel to function.

[lclarkmichalek]

If you're trying to transmit trusted information in clientside js, then one common pattern is to have a user's browser to fire the data initially, then crawl to obtain a trusted copy. The last company I worked for did this, but skipped the second step, which led to all kinds of XSS attacks.