I don't know the history of column span but the reason Firefox was "behind" on standards was because Google was pushing new standards through committee faster than competing browsers could keep up. Google would implement a new feature, offer it as a free standard, then get it through the committee. Because Google already had it in their browser, they were already compliant while Firefox had to scramble.

It was Google doing their variation of "embrace, extend, extinguish"

It got so bad that not even Microsoft had the resources to keep up. They said as much when they said they were adopting Chromium as their engine.

I'm gonna be honest, if they used a feature that wasn't ready for prime time, it's still on them.

This was due to Firefox at the time not implementing web standards that Chrome did.

Uhm, yeah, that's what browsers do. There are somewhere about 150 web standards and some are hard requirement while others are soft. Blink has some implemented that Webkit hasn't but Gecko has and that's true for all three. Same for browsers.

Btw, the one with the most implemented standards is QtWebkit by far. It's still slower tho.

If only one browser runs it, it's not a standard