As there are a lot of new people going to come to PC soon. Here is how to Opt-in to local text chat via the settings. This allows you to chat with people in the tower, social space, and anyone around you not in your fireteam.

To opt-in to automatic local text chat, players should:

• Navigate to the Settings menu
  
  
• Select "Gameplay" in the left-side panel
  
  
• Under "Text Chat", select the "Local Chat" drop-down
  
  
• Select "Automatic Opt-in"
  
  
• Press Enter to save

To manually access local text chat, players may:

Press Tab to cycle through each available chat channel

Type /local (or just /l), and press either space or selecting it from the autocomplete list

https://www.bungie.net/en/Help/Article/46665