Exactly. The fact that that "majority" of "readers" in the US care more about Tumblr means nothing, Tumblr is the farthest away from important when it comes to technology, innovation, and I'll even say communication. It's just another stupid SV deal that guaranteed early investors and VC in Tumblr a nice exit before the wheels fell off that company. Yahoo! has cash and they use it in whatever ways they want.

I'll agree with OP that Yahoo is more relevant to the masses, but we all know the masses are constantly up for Darwin Awards.