Not just tracking cookies, but browser fingerprinting.
Not just Google, but now Cloudflare.
Not easily, and not at the time, no, it really was a very easy way to quickly reduce bot problems at the time.
You’d get random spam for stuff that could flood your forums or etc, and setting up captcha had an extremely immediate and palpable effect on reducing the spam that came in from random bot farms and shit.
I can personally confirm that when I implemented captcha on my forums i maintained 14 years ago, it pretty substantially reduced spammers by a huge degree.
There’s no point in arguing what once was. Things have changed. CAPTCHAs are now less effective, far more invasive, and for many people, far more troublesome.
Cling to them if you like. I no longer use them on any of my sites, because I care about my users.