Может. Но мне так больше нравится, да и для девелопмента удобнее (особенно при обучении): 

* The initializer is loaded once at startup (modifications will show up when restarting the application) and may slow down your application startup, but all RailsAdmin configuration will stay in one place.
*  Models are reloaded at each request in development mode (when modified), which may smooth your RailsAdmin development workflow.

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https://github.com/sferik/rails_admin/wiki/Railsadmin-DSL