I can't help you out with a history of lawsuits to cover damages from faulty open source software, but here's a great little link to explain the legal reasoning for the need for the disclaimer:

https://oss.kemitchell.com/#contract-law

Quickie TL/DR; OSS is ultimately a product offered under a license. Without a warranty disclaimer, if the code proved to be shoddy, unfit for use, buggy, or crashed and damaged your business — you would have the ability to sue: I offered you a product that claimed to do be able to do a thing, and it didn't.