I'd go even further given how easy it is to change IPs to just require it on every case. That simplifies the logic. We already require captcha for every user creation regardless.

In T357778#9551525, @Ladsgroup wrote:

I'd go even further given how easy it is to change IPs to just require it on every case. That simplifies the logic. We already require captcha for every user creation regardless.

We can make that configurable and observe what happens in some pilot wikis (T357763: Create a temporary accounts initiative Grafana dashboard). I hesitate to say that we set "always show a CAPTCHA for temp account creation" as the default, because that diverges significantly from the status quo, in regard to barrier to entry for editing.

Fair, in adding links, the user clicks on Publish and then sees a captcha, maybe if we show captcha before that it would reduce the barrier but yeah. Very non-scientific gut feeling. Nothing concrete.

The proposed mechanism for showing the CAPTCHA is in this patch (T20110: Define AbuseFilter consequence to display a CAPTCHA).