It's more like Yahoo! is overpaying for app development teams. They have to, as they are way behind in mobile and nobody good wants to work there.
I've been saying this for the last three years here on Hn: Yahoo is stupid to not be aggressively and heavily spending their massive cash reserves to buy back into an innovative place here in the valley.
Mayer is no dope! She knows that being the convoluted portal that Yahoo is, is a death sentence. They need to act quick and fast and often.
Buying up a very young tech upstart is a good step toward splicing in some new, nimble DNA - which Yahoo needs desperately.
$30MM is also a marketing number!
Remember when everyone's exit plan was Google or Facebook? Well, add Yahoo to the list for exit acquire players.
Marissa Mayer may be able to stave that off this time around and Yahoo may be able to buy their way into mobile, but when mobile is so hit-driven and short-term, it seems unwise to start spending money on little things like silly TL;DR apps (that you're going to shut down, anyway).
If the deal is about pushing into mobile, Yahoo needs to secure culture changers, not apps. They need to buy the Duartes and Rubensteins and Brichters, and give them full autonomy to run the mobile ship however they please. That's a longer term plan, but it pays off in actual tangible results. $100 says we never hear anything about Summly's technology again, and the kid leaves as soon as his stock vests.
Yahoo is a web 1.0 company, pre-crash and just didn't have it in their DNA to innovate out - like you said, they choked those previous acquisitions to death.
That doesn't mean that the strategy of acquiring their way back to a good position is bad - it was that the leaders previously attempting to do so just didn't have it in them.
I say that Mayer is their last hope.
Sumly is three people and they paid about $30 million for it. Start throwing million dollar /year offers and many "good" programmers will want to work there. This stinks, IMO.