And it still exists (just for the record):
https://www.eurail.com/en/eurail-passes/global-pass
But of course the times have changed.
The huge thing about this was that for most young people at the time the 18 years birthday meant a lot, in most EU countries that was (is) a "threshold" you become to all effects an adult and getting an Eurail ticket was the first "totally independent" travel experience without the family, and you got for an all in all affordable to everyone amount of money "freedom", you met a lot of other young people doing the same, you could try to start a conversations with someone (a "peer") in (actually usually much improvised) other language, you could visit places you had only read about in books, etc.
It was a great experience.
I did two of them and they are some of the best travel experiences I had in my life.