There is no need to destroy privacy, waste resources, create terrible ux, gate content…
There is no need to destroy privacy, waste resources, create terrible ux, gate content…
Automation detection and privacy are orthogonal. The ideal bot detector yields a single bit of information: bot or not. It doesn't need to try to de-anonymize users or anything like that. As for UX, well, spam is a bad UX.
The incentive is money. You can't just wave a magic wand and get rid of the incentive to spam things. Asserting that you can is wishful thinking.
Things that work for small sites fall apart once you get 10~100 million+ people.
Look, I help do the actual user moderation for a large (10m+) subreddit, and it is a god damn nightmare. Plus, on top of that, we have to do automated bot detection anyways, because otherwise it's just neverending bot spam.
Reddit is actually a good example of having millions of users with no captcha. They “fixed” their problem with user moderation.
You chose to become a moderator, so it must not be that much of a nightmare.
EDIT: Reddit does have a captcha now. My guess is it came along with the other users hostile changes in the new design.
edit: They have for at least the last 6 years based on online questions. Long before the new design.