So I don't quite see where the comparison with pump&dump coins comes into play.

I did make the comparison to show that abuse is not something that's putting downward pressure on the price. 99% of coins are abuse yet they have lots of volume and demand.
If you look at how much people are 'extracting' from steem each day and the daily volume of STEEM you will see that it's meaningless.
It would be interesting to see crypto currencies's volume that comes purely from utility.
Most coins would be at less than 1% of their volume. Even STEEM which is a very useful coin have almost all of its volume ( which is low) come from speculation.