Marco Russo and Alberto Ferrari share their thoughts on the CONTAINS() function in DAX:
The CONTAINS function in DAX has been available since the very first version of the language in 2010. In the evolution of the language, new syntaxes and functions have been added, and several use cases for CONTAINS that were valid many years ago are no longer considered good practice. The goal of this article is to clarify when CONTAINS is a good practice and when there are better alternatives to solve common problems.
Read on for that explanation.