Okay, um, assuming you're not being sarcastic, because I am failing to read your tone accurately (if you are being sarcastic, ignore the below):
If all the regulars killfile the trolls, the regulars don't see the trolls. Thus, there is no motivation (or knowledge) on their part to keep the trolls out. Thus, when new people come into the forum, they see a place that is troll-infested and leave, without ever bothering to learn how to set up a killfile.
This doesn't happen to places that are heavily modded, because the mods handle the trolls, but I saw it happen to a several forums in the last days of Usenet (and I've seen it happen in an analog way in RL groups where the regulars have learned to just avoid the unpleasant people, so the unpleasant people drive off all the new members instead.) DW places vary in their modding level, but quite a few of them depend at least partly on the members taking a role in enforcing their norms, and I suspect the places where killfiles got most extensively used would be the lightly-modded places where the problem would be most likely to develop.
I know the DW management is highly in favor of killfiles, though, and I know there are also very good accessibility-ish reasons to get them, so I am not trying to talk you out of it, I'll just to learn to deal with it.
But the same thing can happen in any website where a large majority of the power users are heavily using customization for basic usability/accessibility/social features, where the response to "we need to fix this" is always, "just install this customization". DW Dev is actually very good at keeping a weather eye on what logged-out users see, but I've seen that sort of thing happen repeatedly, so I worry. What often results is a site where you have to be willing to invest a lot of time on learning how to customize before you can even figure out why the site is worth investing time in. Not that there's anything inherently wrong with a social site that consists entirely of the same power users talking to each other, it's just not my preference.
no subject
If all the regulars killfile the trolls, the regulars don't see the trolls. Thus, there is no motivation (or knowledge) on their part to keep the trolls out. Thus, when new people come into the forum, they see a place that is troll-infested and leave, without ever bothering to learn how to set up a killfile.
This doesn't happen to places that are heavily modded, because the mods handle the trolls, but I saw it happen to a several forums in the last days of Usenet (and I've seen it happen in an analog way in RL groups where the regulars have learned to just avoid the unpleasant people, so the unpleasant people drive off all the new members instead.) DW places vary in their modding level, but quite a few of them depend at least partly on the members taking a role in enforcing their norms, and I suspect the places where killfiles got most extensively used would be the lightly-modded places where the problem would be most likely to develop.
I know the DW management is highly in favor of killfiles, though, and I know there are also very good accessibility-ish reasons to get them, so I am not trying to talk you out of it, I'll just to learn to deal with it.
But the same thing can happen in any website where a large majority of the power users are heavily using customization for basic usability/accessibility/social features, where the response to "we need to fix this" is always, "just install this customization". DW Dev is actually very good at keeping a weather eye on what logged-out users see, but I've seen that sort of thing happen repeatedly, so I worry. What often results is a site where you have to be willing to invest a lot of time on learning how to customize before you can even figure out why the site is worth investing time in. Not that there's anything inherently wrong with a social site that consists entirely of the same power users talking to each other, it's just not my preference.