When you use a captcha, you presumably want to defeat someone curling your CreatePost endpoint, not just make it more annoying to do it at only botnet scale.
This captcha still lets all traffic through. Except now you waste the battery of honest users.
Even HN proponents of the idea don't use it on their own sites.
I rather see something like anubis than some unsolveable captcha. I never understood the battery-argument, I recon my screen uses more energy during pow-solving than it takes my phone to solve these pows.
Every time a new submission is created on HN, you have a curl script that posts a comment on it shilling your product. (According to the /newest tab there seems to be one submission every few minutes.)
What's harder for you to automate: the comment always posts successfully after 500ms, or you get a Cloudflare Turnstile captcha every time?
This captcha still lets all traffic through. Except now you waste the battery of honest users.
Even HN proponents of the idea don't use it on their own sites.