[oehpr]

I don't find highlighting text on mobile to be too difficult, so I don't see that as a barrier imo.

for disabilities well... That one I dunno. I don't have a good concept of what kinds of UI are most convenient for each type of accessibility case.

And it's a little tempting to get lost in the weeds of who watches the watchers, but to be honest even if implemented in hacker news case, the mods themselves could vet flags for anomalies. Just this on its own would serve as a force multiplication for HN mods.

For more decentralized forms of moderation. One method might just be a simple flag appeal. Circles back to the community, they can discuss if the rule that is cited is fair, and if it wasn't possibly remove or limit flagging abilities of those who cited the rule incorrectly. And possibly some increased punishment if the appeal fails? There are lots of options there. Big wide design space.

I do think the direct text highlighting has a few important features. The Sybil attack resistance is one. That was one of the OP's primary concerns. Also, clarity on what rule was broken and why is very important, and a given rule can be verbose. It might not be obvious what specifically in a given rule was the reason for the violation. Direct highlighting lets flaggers more directly communicate what the issue is, without opening the communication channel up for a flame war.