By definition, new apps wont have any deprecations to worry about. So dont expose those controls for new apps by default (rails#51831)

Author: dhh

railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt

@@ -50,12 +50,6 @@ Rails.application.configure do
   # Print deprecation notices to the Rails logger.
   config.active_support.deprecation = :log
 
-  # Raise exceptions for disallowed deprecations.
-  config.active_support.disallowed_deprecation = :raise
-
-  # Tell Active Support which deprecation messages to disallow.
-  config.active_support.disallowed_deprecation_warnings = []
-
   <%- unless options.skip_active_record? -%>
   # Raise an error on page load if there are pending migrations.
   config.active_record.migration_error = :page_load

railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt

@@ -52,12 +52,6 @@ Rails.application.configure do
   # Print deprecation notices to the stderr.
   config.active_support.deprecation = :stderr
 
-  # Raise exceptions for disallowed deprecations.
-  config.active_support.disallowed_deprecation = :raise
-
-  # Tell Active Support which deprecation messages to disallow.
-  config.active_support.disallowed_deprecation_warnings = []
-
   # Raises error for missing translations.
   # config.i18n.raise_on_missing_translations = true