I still don't get the point of this. I see the utility of seeing multiple fonts at once, but I'm sure there is a more subtle point. Because web designers want font families, not just fonts, what does this even mean?
He's saying that fonts that have multiple weights/styles are also fonts that are more likely to be higher quality.
Personally, I would use this tool to find a font that could be used throughout the page for different elements: such as body text, heading text, quotations, etc. The alternative would be to mix and match different fonts, but this takes a lot more effort and experimentation.
This.
I am trying to only use FOSS fonts, also for print, so having families matters even more to me. I actually went through the while directory and sorted it by hand just last month, so this service will prove invaluable next time i need to choose fonts for any project, especially cross-media.
"Google Web Fonts is an awesome source of free, open source fonts hooked up to a world-class CDN. It’s also, sadly, filled with one-off novelty fonts vying for the title of “the new Comic Sans.”
"I quickly discovered that a good metric for higher-quality fonts was the presence of at least one alternate. The Google Web Fonts directory does not allow that type of filtering, so I built this simple one-off page that allows you to browse multi-variant typefaces."
From here: http://somadesign.ca/2011/better-google-fonts/