let me put it this way:

Scenario:

Host 1 - SQL Server 2012 DB Engine and Agent.

Host 2 - SSIS 2012

Package would execute successfully if executed from Host 2. If executed from Host 1 (where the Agent resides, with the ultimate intention of running as a job), it produces the error

To fix, SSIS 2012 components had to be installed on Host 1.