Sure, the people who make the AI scraper bots are going to figure out how to actually do the work. The point is that they hadn't, and this worked for quite a while.
As the botmakers circumvent, new methods of proof-of-notbot will be made available.
It's really as simple as that. If a new method comes out and your site is safe for a month or two, great! That's better than dealing with fifty requests a second, wondering if you can block whole netblocks, and if so, which.
This is like those simple things on submission forms that ask you what 7 + 2 is. Of course everyone knows that a crawler can calculate that! But it takes a human some time and work to tell the crawler HOW.
It’s ineffective. (And furry sex-subculture propaganda pushed by its author, which is out of place in such software.)
The “only one army” concept is how governments remain governments.
If you could raise and pay a competing army, the state’s monopoly on “legitimate” violence becomes threatened.
This is why most states also heavily restrict private access to arms. Interestingly enough, it is also why the United States explicitly protected it: to specifically prepare for (and protect the right to) violent revolution.