Yes, no proof of a definite stall, although the stall warning (stick shaker) did activate seconds before impact with the sea wall. At that point the pilots had pulled full back on the control wheel, and so even if a stall occurred the tail could impact first since the plane was in a high nose-up position.
As usual, there were multiple points of failure that led to the accident. The pilot flying was experienced but new in the 777. The glide slope at SFO was out of service for runway modifications, Asiana pilots relied heavily on automated flying, and the pilot later said he wasn't comfortable with a visual approach. The crew didn't understand nuances of the Boeing auto-throttle and failed to understand that their autopilot setting changes earlier had put the auto-throttle into "hold" mode. They thought the auto-throttle was active or would "wake up" and protect against an unsafe low airspeed.
Target landing speed was 137 knots. The crew finally recognized their speed and altitude were too low at 90 feet, 110 knots, 7 seconds before impact with the sea wall. They applied full power then (throttles had been at idle). NTSB simulations found that if full power had been applied 12 seconds before impact the crash could have been avoided.
So, yes, while there were some confusing quirks of the auto-throttle that many pilots didn't fully understand, three pilots in the cockpit watched or flew an airplane into the ground because their throttles were set to idle, the auto-throttle was not active, and their speed deteriorated well below what was needed for safe flight.
http://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1401.pdf