The idea is to keep the bots out, right? Just one obligatory captcha per month if you want to post something at a random day and swoosh the net is clean again. However these captchas need to be updated regularly and a time limit would be a good idea. Fail to solve the captcha and you're in for more. Might be a good idea even for steemit. You don't want no bots messing with your crypto, right?
Interesting suggestion, but people can still just manually input the captcha once per month and then can use the bots for the rest of the month. I would suggest instead a daily captcha or something more regular, because in my opinion it stops the bots because they have to do it more often. It really doesn't take too long to solve a captcha for a real user, what's your opinion on this?
I think that however the implementation looks like it will be an improvement. Key feature would be more captchas should you fail to solve one.