I don't understand the point of the question. Governments in the UK and US are theoretically accountable, yet we have messes like Brexit and Trump (goodbye this week to net neutrality). In my other hometown of San Francisco, supposedly a bastion of liberal progressive values, our $9 billion budget is bigger than that of 100 countries', yet homeless people run rampant on the streets, vandals break car windows with impunity every single day, and property prices are even more out of control than HK.
I suppose it could be worse, but in a place like Hong Kong, in its current state, suddenly adding accountability might not do much. At best, it will be like when city officials in SF get fired, and taxpayers foot their 6-figure severance packages.
Democracy doesn't work because San Francisco has homeless people?
Each democratic systems needs constant review. The US system needs to deal with gerrymandering