The Chinese volumes were an effect of: first no fees - this has changed, second bots used for inflating the volume - this should also be over as this was required by the authorities, third possibly by completely fake numbers generated by the exchanges - this should also be over as required by the authorities. This is well established now and it is a good explanation - that's why nobody asked Bobby Lee about it. No withdrawals can add to diminishing the volume even further - but it is not the primary reason - you are right there.
No fees policy would not influence the volume in this order of magnitude. If you take a look at the graph, it's almost 450x lower volume then before, that's 45000% lower than before. I don't know about what type of bots are you talking about, if you are talking about trading bots there is still an evidence that they are still there, because exchanges are moving synchronously to CNY exchanges or vice versa.