they mine and they dump for low prices. if you have $ to buy, you get coins at a good price
Certain coins should be dumped as the risk is too high to hold.
But FLT and a few other coins have a very very high chance of greatly increasing in price in the near future.
So many people who know this will take the risk with these more innovative coins to hold their coins and ask for a higher price.
This ^^^ keeps the price rising.
Multipools offer no such opportunity. They just dump it all - all the time.
Fine for other coins - but makes less sense with FLT. Making it hard for them to mine FLT will raise the price and reduce forks.
There is a chance for a 1000% increase on this coin that is almost no chance on most other coins.
So it's worth the risk to hold. In this case.