>How is that being fair? Does you not having heard about it define what is a great product, and what is not?

It's fair because MANY people had never heard of it. I even heard on those same Leo Laporte podcasts people going "what's inbox", people who report on tech for a living. I imagine, compared to people just using the gmail app or the web interface, it had terrible adoption rates which made it not worth supporting. From all I could gather is it was almost exclusively used by those in tech and then only by a small subset.

I imagine reader had a small user base. RSS feeds are a pretty obscure thing and always were.

The only hangouts messages I've ever received have been group spam and likely has a relatively small user base.

Google Circles was largely spam and garbage content created for SEO in my experience and probably had a very small real user base.

Etc etc. If you your user base is a small percentage, or a fraction of your percentage, of your overall user base it's perfectly fair to go "well, let's shelf that".