Sadly any capitalistic company fails for the same exact reasons. They can't continue making more and more money every quarter, so they call it a failure and give up. To these company's, having a stable business is worse than having a failed business. Because a least a failed business can be sold off for parts.
True, but that's the consequences of their choices years ago. They owners sought constant, quarterly growth in Tumblr to validate their multi-million (or billion) dollar purchase. And rather than building a company that's stable, they were just burning cash and throwing shit at the wall to see what stuck to make that profit trendline go up.
But Tumblr users are very hostile against, really, any changes to how Tumblr operates. It just alienated a lot of us, which isn't going to help them in terms of profit.