I also had to login with my google account to read it.

Logging in to Google Groups has been mandatory forever if you had logged in to a Google account before in that browser. If there are no traces of past login sessions (such as when using Incognito mode) then it opens just fine for unauthenticated users.

One of the annoying things about Google is that if it detects that at some point in the past you were logged in as a user it will not let you see Google Groups content without logging in (or going incognito).

There is no "just let me see the content, I can't be bothered to type my password right now" option, there is no "forget that I'm that user" option, the only option is to log in or to go incognito.

It's how mailing lists were supposed to work circa 1992. But web archives for mailing lists are more than 20 years old. [1] And honestly, I'm not sure "supposed to work" is correct. It's how they did work, sure, but thinking back to the mailing lists I set up pre-web, the goal was to create a forum many people could use. That a mailing list was used to do that was a function of the available tech and how people connected.

And I'll note that from what I can tell, forum software predates mailing list software. LISTSERV only goes back to 1986. [2] Forum software goes back to the mid-1970s [3], and the WELL was started in 1985 [4]. So I think it's reasonable to argue that online forums are the "real" experience, and mailing lists were more an implementation constraint for the decade or so that email popularity outstripped the richer interfaces of the terminal era and the web era.

[1] http://www.lsoft.com/corporate/history-listserv.asp

[2] https://en.wikipedia.org/wiki/LISTSERV

[3] https://en.wikipedia.org/wiki/CONFER_(software)

[4] https://en.wikipedia.org/wiki/The_WELL