Twitch poll decided that it should be required to somehow need some villager trading for progression.

Possible implementations

• Rely on items that can only be obtained by trading with a villager
• Modify villager trades, adding new ones.

Issues

• Villager trading can quickly be quite annoying to players
• JER documentation for trades is not customizable,
  It should be made sure that any added trades are shown in JEI so players don't get confused
• There is no way for automated villager trading, so this must be considered in all dependant recipes

I want to note that I really don't like this idea because of the named issues.