The afni_proc.py output also contains a summary of useful quantitative features. This can be put into a simple AFNI command to apply drop/exclusion criteria for subjects automatically. In this way, one can integrate both qualitative and quantitative QC efficiently.
Why else is visualization of data helpful? Consider afni_proc.py's QC HTML images of EPI-anatomical alignment (latter are overlay edges). This makes it easy to spot localized signal loss/dropout, distortion, and more. Want to study the subcortex? Better check signal there!
As part of the FMRI Open QC project, we discuss combining visualization and quantitative criteria in AFNI, particularly with afni_proc.py:
Quality control practices in FMRI analysis: Philosophy, methods and examples using AFNI (Reynolds et al., 2023):
https://www.frontiersin.org/articles/10.3389/fnins.2022.1073800/full