Debian Stretch had just been released a few month ago and only supports PHP 7.0 with the official repositories. Which means that ezplatform 2.0 cannot be installed on this OS because of the php 7.1 requirement in the composer.json (please don't tell me to use remi repositories).
Ezplatform is based on Symfony 3.4, which is compatible with PHP 7.0. So why enforcing the PHP 7.1 version in the composer.json. Is ezplatform 2.0 really incompatible with the 7.0 version ?