I think the reason for the IE8 support is that there are still lots of old windows machines used in china.
And if you think IE8 is bad, have you ever had to support IE6? ;-)
At Social Amp (2012), I was making cross domain single-page applications for sites like 1-800-Flowers, where we had to support back to IE6, but, since a tag was missing from the main website, we had to do some hacks to "shore up" IE6 so the padding would be there.
It's feasible to have some pretty sweet JS (backbone.js, easyxdm) on IE6. The limitation came from the engine's performance, stylesheet and js caps, and really strict rules on, dangling commas (memory is a bit fuzzy in which instances, but it'd crash our whole script). In some cases, there'd be no errors, and it'd just freeze it.
[1] https://en.wikipedia.org/wiki/Internet_Explorer_box_model_bu...
Back in the day it was quite a PITA though.
Jesus... And I thought IE11 was bad (enterprise SaaS such as Salesforce is dropping its support already).
I’ve tried to run IE11 debugger on Virtualbox and it was slow as molasses.