Comments are social signals. Their impact is much less than Twitter, FB, Reddit are nowadays (because they are often faked) but anything which is a social signal is considered good and most often even "credible" and may increase the live traffic Google sends even.

One of the often forgotten tricks are Facebook ads. When an ad leads to increased live traffic (1-1.5K clicks daily), Google will almost instantaneously start sending additional traffic to the site as it discovers that spike. Obviously, sites with Google Analytics implemented are at an advantage here since Google discovers that traffic much sooner and also has cleansed data (not someone in his basement faking the traffic with a FB referrer lol). But asides from the privacy issues, GA also means that Google has detailed site performance data (loading times, bounce rate, aso) which may have a negative impact when a site is dealing with issues like node issues.