Google's John Mueller said he would advice that if "that's something where if you see that these pages are important enough that people are linking to them then I would try to avoid blocking them by robots txt."
In short, if you have important or popular pages with a lot of links to them, make sure Google can access the page.
If you robots.txt out that page, Google may drop the links and those links won't help Google understand the true importance of your web site. That means, your rankings can decline in Google Search.
Of course, it all depends on the specific situation of that piece of content. So this is not simple blanket advice across every situation.
Here is the embed where John said this at the 6:44 mark into Friday's video:
Forum discussion at YouTube Community.
