There's that "its just this one clan" again
How many Dalish clans do we need to see blow themselves up before you realize something is inherently flawed in their actions
The fact that Gaider has addressed that the Dalish clans are all different:
The Dalish have the Gathering every 10 years, where all the clans are supposed to gather and the Keepers of each clan share their knowledge with each other. This is also where Dalish-wide issues are dealt with, and ideally the Gathering is supposed to keep the Dalish roughly in step with each other. In practice, though, you are correct. Each clan tends to go the way that its Keeper dictates. Some clans are very militant, almost xenophobic. Some are little more than bandits in whatever wilderness they've staked out (this is often the case in Tevinter, for instance). A few are quite benevolent and live in peace with nearby humans -- the Rivaini city of Llomerryn is known to have a semi-permanent Dalish encampment on its outskirts, and trade with the elves for their crafts is encouraged.
As he pointed out, the clans can vary quite a bit, in good and bad ways, so I don't have the inclination to condemn them all because of the actions of one single clan from "The Masked Empire".