Last release of IE6: 2008
Concerted campaign to make everybody stop using IE6: 2009
Microsoft joins that campaign: 2011
First release of React: 2013
That colored a lot of low-level decisions about how events were implemented, false claims about virtual DOMs being fast or efficient, and especially the culture of adding dependencies because you need a feature which wasn’t in Internet Explorer. Once that trend is established, it’s hard to change without breaking compatibility and so you end up with people in 2025 using slower code based on the support matrix set over a decade earlier.
(And to be clear, I’m not saying that React has no redeeming values - only just it’s healthy to reconsider decisions made in previous decades to see whether the cost/benefit ratio has changed. I think we’re going to see some really interesting shifts as funding for open source shifts in a non-boom economy, but also as LLMs adjust the working style & relationship many people have to maintenance.)
That said, I was on a team that was still supporting IE6 around 2014. We had clients, mostly in China from what I heard, that were required to use it because internal tooling had developed around it and their IT teams wouldn't let them upgrade.
It was definitely frustrating knowing that a better world was possible but not quite there.
One of the things I realized while working on it was that it was easy because I’ve learned the web platform over the years and was able to use builtin features rather than reaching for more libraries, but a lot of younger developers only ever really learned React and are stuck the IE6 era it was designed around. That allows them to be productive, of course, but it often means that people take on layers of dependencies because once they’ve invested a lot in that path the cost of switching is really high.