You do need to setup the Migrate plugin if you are running jQuery prior to the 1.9 version.
However, older scripts may have deprecated code and you will need Migrate if you use jQuery 1.9 and over.
Warning Use Migrate 3.0 when using jQuery 3.0 and over only. Do not use jQuery 3.0 if old scripts still show errors/deprecated messages when using earlier versions of jQuery and Migrate.
Tip You can see the Migrate hints and diagnose compatibility issues when using the jQuery Easy plugin with the libraries uncompressed.