> why wouldn't they use one of the techniques that successful discussion forums employ to filter out spam, extremism, and other noise?
They have done.
Removing comments will reduce some engagement, but as pointed out they've come to the conclusion that the sort of engagement lost is of low value to the majority of their target audience and comes with a cost (in terms of moderation effort) that isn't worth, to them, any residual "good" value the comments sections have.
>HN being an obvious example
I think a key difference between HN and news pages like those in the enquirer in this matter is that their comments area is more of an afterthought to start with where much of the purpose of many visiting HN, good sub-reddits, and do forth is for the comments. This means removing them would be much more sufficient a loss. It also means that for a greater part community moderation works, reducing more costly (for the need site) central effort (it is still needed, of course but the cost/benefit balance is very different).
They have done.
Removing comments will reduce some engagement, but as pointed out they've come to the conclusion that the sort of engagement lost is of low value to the majority of their target audience and comes with a cost (in terms of moderation effort) that isn't worth, to them, any residual "good" value the comments sections have.
>HN being an obvious example
I think a key difference between HN and news pages like those in the enquirer in this matter is that their comments area is more of an afterthought to start with where much of the purpose of many visiting HN, good sub-reddits, and do forth is for the comments. This means removing them would be much more sufficient a loss. It also means that for a greater part community moderation works, reducing more costly (for the need site) central effort (it is still needed, of course but the cost/benefit balance is very different).