Drupal 6/7 was actually what led me to discover headless and JS :) After I learned it and built a few features & Features, I thought to myself, "Huh, okay, I see what they're getting at here... it's pretty powerful, just hard to use. Wonder if there's an easier way to do this..."

Turns out, absolutely yes! I guess there's a reason why headless and JS exploded. We migrated and never looked back.