Do we have to use config.load_defaults?

After upgrading to 5.0, we used the rails update:task rake command to generate the framework defaults file(s), but years passed and we never actually turned any of the new defaults on.

Fast-forward to now and we’re in the middle of a Rails 6 upgrade. We see that we still have those framework default files and everything’s still commented out.

So my question is multi-part:

  1. Do we run the risk of something completely breaking if we release Rails 6 without having enabled the Rails 5 defaults? Isn’t it safe if we just don’t ever call config.load_defaults 6.0 in our application.rb file?

  2. If the answer to the above is “No risk”, then what’s to stop someone from just never calling config.load_defaults and simply ignoring the new defaults introduced with each Rails version?