To add a bit of empirical analysis to this comment, I analyzed the YCombinator Winter 2015 batch. I categorized the startups into one of three buckets: Tech-Dependent Business Model (TDBM), RePackaging and Polishing existing tech (RPP), and Novel Tech (NT). The list can be found here.

• CampusJob - TDBM
• Seed - TDBM
• NextTravel - TDBM
• TheMidGame - TDBM
• eBrandValue - TDBM
• Standard Cyborg - RPP, maybe NT
• Rescue Forensics - TDBM (social entrepreneurship)
• Lumi - TDBM/RPP
• Undeground Cellar - TDBM
• Transcriptic - NT?? but not easily evaluated
• Atomwise - maybe NT but probably RPP/TDBM of machine learning (I doubt they created new ML algos)
• Spark Gift - TDBM
• Gradberry - TDBM
• Industrial Microbes - NT?? but probably TDBM/RPP of existing chemical engineering tech
• TechList - TDBM
• Meadow - TDBM
• ReSchedule - TDBM
• Diassess - RPP, synthesis of biotech and infotech
• RazorPay - TDBM
• DirectMatch - TDBM
• BuildScience - TDBM/RPP
• ShiftLabs - RPP, making medical devices cheaper.
• Valor Water Analytics - TDBM
• Instavest - TDBM
• Open Listings - TDBM
• CloudMedx - TDBM/RPP
• BankJoy - TDBM
• TransitMix - TDBM
• ZenFlow - NT, in biotech space.
• Final - TDBM
• Lully - maybe NT but probably RPP
• Spire - TDBM/RPP
• AnalyticsMD - TDBM
• Smarking - TDBM
• 20N - NT
• GrubMarket - TDBM
• CribSpot - TDBM
• KickPay - TDBM
• Notable Labs - uncategorizable but brilliant, some kind of legal/biotech/infotech combination play
• Pretty Instant - TDBM
• VetPronto - TDBM
• Akido - TDBM
• DroneBase - TDBM
• MashGin - maybe NT in computer vision space but probably RPP/TDBM
• LabDoor - RPP/TDBM
• Bonfire - TDBM
• EquipmentShare - TDBM

The following pattern emerged from this exercise: YC is not funding startups that are developing new computer science technology, with the possible exception of MashGin and AtomWise. The YC startups that are attempting to develop new technology are in the biotech/medtech space - Transcriptic, Standard Cyborg, Industrial Microbes, Zenflow, Lully, and 20N.

Edit I noticed after writing that the list is from Demo Day 2, representing the second half of the Winter 2015 batch. However, it doesn't appear to me that analyzing only half the batch causes a serious bias in the conclusion. The Demo Day 1 batch is available here.