In this excellent Mashable article about Yahoo's disastrous $1.1 billion purchase of Tumblr and its subsequent mishandling is this bit:
Top Yahoo executives clashed with Tumblr, or just flat out confused employees. On one occasion, an executive overseeing [Tumblr founder and CEO David Karp] and his division perplexed employees by saying he thought Tumblr had the potential to "create the next generation PDF," according to multiple sources.
And that is why Yahoo became the next generation fax machine. Read the rest