Perhaps, although when I search on Taobao, prices are still expressed as a discount from the full Y/J class fare using an x.x折 format across all airlines, so it's hardly a free market. HRB-PEK has 4-5 airlines on it depending on if the regulators consider HU and CN separate airlines or not, so maybe it's escaping market liberalisation due to being under 5 airlines on the route.

One thing that might also keep airlines honest, particularly on shorter routes, is the spread of HSR in China, which still has set prices. Harbin-Beijing is still uncompetitive, with the fastest service still just over 7 hours (vs 2 hours gate to gate). However from January 1st the Shenyang - Beijing HSR should open and cut at least two hours from that so the train will start looking more attractive. So that should keep airfares under control on this route at least.