where is the problem? which startup has been killed by patents? given that the US has the most successful entrepreneurial system - what exactly makes this a huge problem?
I have, however, gotten cease and desists based on trade mark. I had a name that was of the type Adjective-Adverb. A company claimed it owned all use of the Adverb word because they'd registered some other two word name that included the same word. I Thought it was hilarious. They weren't even registered in the same business area as I was operating-- yet they sent me several 30-40 page threatening letters and "license agreement/settlement" contracts for me to sign via FedEx. I just tossed them and laughed.
It's not just the start-ups that you see that might be killed it's all those that you never get to see or hear about in the first place, killed before they ever left the drawing board.
Start-up founders are savvy enough to take patents into consideration when they embark on a new venture, to do otherwise would be extremely foolish.
As for whether or not patents can kill companies, I've been on the receiving side of these suits and were it not for the fact that I had a main office in a country that is a bit more down-to-earth when it comes to legislation it would have certainly killed the start-up I was CEO of.
A lot of patent trolls will canvas small businesses and extort settlements. The bigger cases that you would hear about are usually when litigation happens - but by that point its when the company is no longer a start up and large enough to be a profitable litigation target.