I’m starting a new site, and executed:
composer create-project drupal-composer/drupal-project:8.x-dev --stability dev --no-interaction
After all of the installing and downloading messages, these appear:
symfony/var-dumper suggests installing ext-symfony_debug () psy/psysh suggests installing ext-pcntl (Enabling the PCNTL extension makes PsySH a lot happier :)) psy/psysh suggests installing ext-readline (Enables support for arrow-key history navigation, and showing and manipulating command history.) psy/psysh suggests installing ext-pdo-sqlite (The doc command requires SQLite to work.) psy/psysh suggests installing hoa/console (A pure PHP readline implementation. You'll want this if your PHP install doesn't already support readline or libedit.) symfony/dependency-injection suggests installing symfony/proxy-manager-bridge (Generate service proxies to lazy load them) alchemy/zippy suggests installing guzzle/guzzle (To use the GuzzleTeleporter with Guzzle 3) zendframework/zend-feed suggests installing zendframework/zend-cache (ZendCache component, for optionally caching feeds between requests) zendframework/zend-feed suggests installing zendframework/zend-db (ZendDb component, for use with PubSubHubbub) zendframework/zend-feed suggests installing zendframework/zend-http (ZendHttp for PubSubHubbub, and optionally for use with ZendFeedReader) zendframework/zend-feed suggests installing zendframework/zend-servicemanager (ZendServiceManager component, for easily extending ExtensionManager implementations) zendframework/zend-feed suggests installing zendframework/zend-validator (ZendValidator component, for validating email addresses used in Atom feeds and entries ehen using the Writer subcomponent) symfony/validator suggests installing symfony/intl () symfony/serializer suggests installing symfony/property-access (For using the ObjectNormalizer.) symfony/serializer suggests installing symfony/property-info (To deserialize relations.) paragonie/random_compat suggests installing ext-libsodium (Provides a modern crypto API that can be used to generate random bytes.) easyrdf/easyrdf suggests installing ml/json-ld (~1.0) phpdocumentor/reflection-docblock suggests installing dflydev/markdown (~1.0) phpdocumentor/reflection-docblock suggests installing erusev/parsedown (~1.0) pear/console_table suggests installing pear/Console_Color2 (>=0.1.2) drush/drush suggests installing ext-pcntl (*) drush/drush suggests installing drush/config-extra (Provides configuration workflow commands, such as config-merge.) behat/mink suggests installing behat/mink-selenium2-driver (slow, but JS-enabled driver for any app (requires Selenium2)) behat/mink suggests installing behat/mink-zombie-driver (fast and JS-enabled headless driver for any app (requires node.js)) sebastian/global-state suggests installing ext-uopz (*) phpunit/php-code-coverage suggests installing ext-xdebug (>=2.2.1) phpunit/phpunit suggests installing phpunit/php-invoker (~1.1)
Are any of the above really necessary for Drupal to run efficiently and smoothly?