Infrastructure monitoring is only one aspect of the complete Dynatrace monitoring picture. It's most effective when combined with server-side service monitoring and mobile & web application monitoring. This is because each Dynatrace monitoring perspective is intertwined with the other monitoring perspectives.
Infrastructure exists to support the services that collectively are perceived by users to be your web application. The purpose of infrastructure therefore is ultimately to provide users with an excellent user experience. Issues that manifest themselves as performance degradation on a user’s device can often be traced back to underlying infrastructure issues.
In other words, if you only monitor infrastructure, you'll only see infrastructure problems from the perspective of an outsider. You won't understand the context of your infrastructure in relation to your application and its underlying services. Only if you monitor infrastructure along with server-side services and the real-user experience that your users experience on their devices are you able to gain a holistic understanding of the entire software environment that supports your business.