Earlier quoted context omitted.
I think that was the only way at that point to bring in fresh creative talent. No creative person probably wanted to quit their existing job and leave for Yahoo at that point. And why would they? If you're really talented, you could either go work for Google/Facebook/etc. (if you want a stable life), or start your own company (if you're adventurous). Yahoo was stuck in the purgatory somewhere in between.
I don't really buy this argument. There are reasons for acqui-hires, but it's usually to bring on board a strong existing team, a world-class domain expert, or a tech base with employee support. Summly was none of those. They got one 17 year old dev, and a fairly-decent product they made basically no use of. I don't know how good D'Aloisio is, but he's not that good. Especially without the kind of status and support…
While I don't know if all these dictionaries and calibrated weights of parameters were really worth $15M, I'm positive that such an IP was major reason of the acquisition.