Nope, that only works if there weren't botnets that just multiplex millions of requests over thousands of websites.
Anyone who has tried IP-blocking bots has run into this where 50k+ IP addresses just need to send you one request per couple minutes.
Your posts in this thread show how easy it is to be against recaptcha without addressing why people use it, or you suggest it's a flawed security model when people use it. It's kind of hard to take your advice seriously when I think of real world websites fighting real world abuse.
In another post of yours, you recommend the web developer to just expend more and more effort to circumvent abuse without recaptcha. Like creating a whole pending message system for, say, a forum instead of just a contact form. In fact, you'll find that there's no shortage of work for you to do once you attract abuse. And that's an easy solution to prescribe when you have no skin in the game. God forbid the site doesn't even make any money.