I think you do not understand why website owners use captcha. Website owners use captcha services, because doing so saves money for them.
Captcha will stop saving money, if the captcha becomes so ineffective that the short-term and the long-term downside (annoying users who are subjected to captcha) exceeds the cost saving ("cost" here is potentially many different things - it could be quality of service for normal users, it could be opportunity cost, it could be the cost of serving the traffic like network bandwidth or cpu or database capacity).
Captcha will stop saving money, if the captcha becomes so ineffective that the short-term and the long-term downside (annoying users who are subjected to captcha) exceeds the cost saving ("cost" here is potentially many different things - it could be quality of service for normal users, it could be opportunity cost, it could be the cost of serving the traffic like network bandwidth or cpu or database capacity).