You're understanding of trolls is flawed. A troll will generally make sure their messages show up (using incognito mode, tor, etc). Think about it, the people who don't check to see if they're shadow-banned are the ones that don't expect to be banned. Trolls very much expect to be banned. It's their modus operandi.
The only people you're effectively hurting are the ones who think they are making useful contributions but make the unfortunate mistake of hurting the moderator's feelings.
Trolls generally don't expect to be shadow banned they expect to be banned. Until they figure that shadow banning exists it's a very effective method and once you realize you make them check if they've been shadow banned regularly so it effectively doubles their work. Quite often their willingness to invest time into trolling drops off with lack of response so often they will leave before they understand that shadow banning is a thing.
>Trolls generally don't expect to be shadow banned they expect to be banned.
I disagree with this assertion. Shadow-banning on HN is quite well known, and any troll worthy of the term understands the landscape of their endeavors.
>banned regularly so it effectively doubles their work
How is opening a link once a day or so in incognito mode to check for their comment effectively doubling their work?
>Quite often their willingness to invest time into trolling drops off with lack of response so often they will leave before they understand that shadow banning is a thing.
Again, I think we both have very different ideas on the transience of a trolling campaign. I assure you, once someone is determined to troll a specific community, its a much longer commitment than you are estimating.
Edit: Impressive. Down-voted for stating my disagreements with counter-points.
I voted you back up because what you're saying is interesting. But please, everybody: enough with the complaints when you're downvoted. It happens to all of us and there isn't a thing you can say about it that isn't old and boring and makes you look bad. It's the worst HN trope there is, so just move on.
If the downvote was unfair, someone often comes along and fixes it; and if it was fair, then you should reflect on what you said. Either way, the impulse to complain should be held in check.
I honestly can't see how/why people care so much. Maybe I'm not doing HN right, but I usually don't have a lot of time to read a thread and make a cogent comment and stuck around for discussion. This is unfortunate; I think discussions are better than just one-off comments. But add to this the vanity of checking if my comments have been downvoted? Man, I've got better things to do.
From my personal experience having dealt with trolls on other popular forums and implementing shadow bans myself previously my experience runs counter to your beliefs.
You don't have to catch every troll with shadow bans. You make the experience for the new ones unenjoyable by removing their feedback and they are more likely to move on before they become committed enough to start cycling accounts.
If someone is determined to troll a community than no form of protection other than brute force moderation will work but compared to the number of trolls out there the number that rise to that level of abuse are very small.
The only people you're effectively hurting are the ones who think they are making useful contributions but make the unfortunate mistake of hurting the moderator's feelings.