You were probably thinking about geeks leaving heartwarming comments under a forgotten repository while reading this.

But what really makes a trace valuable? Internet growth has proven that scaling traces does not really grow value to the same extent.

  > Leaving something adds a little humanity to the internet.

At this exact moment in time there are literal thousands of creators that chase external validation, and millions of lurkers leaving 1-bit "like" reactions under their content. Let's go to popular instagram pages in a search of humanity.

  > It helped you, so it’s likely a useful idea

Billions of reactions left on social media so far proved to be very poor indication of quality.

  > You now have a profile you can access that collects the things you found noteworthy

In a world of content abundance one rarely has time or motivation to re-visit everything he/she reacted upon. This also works increasingly worse the more "traces" you leave, see #1 and #2.