Hello,
The use of doctrine is confusing with Symfony since doctrine/migrations:"^3.0" version.
The Symfony documentation still encourage to download the whole bundle like this :
composer require symfony/orm-pack
composer require --dev symfony/maker-bundle
But these commands will install doctrine/migrations:"^3.0" which doesn't support multiple options described in the maker-bundle.
For example, --db=DB and --em[=EM] are not supported anymore.
Maybe we could update the documentation and the symfony/orm-pack to allow keeping previous doctrine/migrations versions which support those options ?