You're behind the times. It's not widespread but it's been happening for years.
Also the other day selenium author (iirc) said they are working on such a thing for "automated testing"
So this proposal will do nothing to prevent bots; maybe increase the cost a little.
On the other hand, it will surely discriminate people, new emerging technology and companies. No other search engines can be built. No new browsers. No openness.
Anyone supporting this proposal is either pure evil or stupid or both.