I think, the primary benefit of having data standard for clinical trials is to improve Data Interoperability,, each site may collect data in different formats/terminology to explain similar variables and this is challenging and time-consuming to merge and compare data from the clinical trials, so if all sites have standardized data formats and terminology, they will have the ability to easily share, merge, and analyze data across the study as well as this will ensure consistency in data collection and interpretation. For example Site A collect data on blood sugar levels using different units of measurement (e.g., mg/dL vs. mmol/L) and Site B and C might use different terminology to describe the same variables, such as blood glucose vs plasma glucose or each Site records the duration of blood sample collection for the study in weeks and months.
It’s better to standardize to set all clinical trials sites perform and collect data according to formats and terminology established by organizations like the Clinical Data Interchange Standards Consortium (CDISC), all clinical trials could collect data using the same units of measurement, standardized terminology and data structures.