I think one of the main causal mechanisms is that corporate cultures do not associate internal tooling with revenue, directly. It is seen as a small cog in a large engine that just has to work. It isn't seen as something that would directly impact customers or drive ROI. So.. they end up being neglected and extremely terrible.
Vine provided an outlet for otherwise unknown individuals to create a name for themselves with minimal effort. Truly a shame that we lost this platform.