Simple.
Any half-decent dps will know when they are going to be bursting more damage, generally in opener, and should throw in quelling before hand. note HALF-DECENT. a lot of what you find in df, are not. Throw in the fact that quelling doesn't actively appear to do anything, a lot of people don't even know what it is (it doesn't increase your numbers etc). I wouldn't say it's common, but I've run into people that are completely oblivious to any moves that don't openly benefit themselves (eg Goad, E4AE, Apoc, Quelling etc)


then again, if you're pulling trash in small groups, you have to be prepared that quelling won't be up for every pull. i'll use it whenever I can, but those fire IVs can hit hard, is annoying when I moaned at for not using quelling and pulling hate, and then I'm like "yeah I used it on the last pack of three mobs you pulled"