Subreports are powerful.
They are also very easy to fall in love with.
Subreports Add Another Reporting Layer
They can make maintenance, performance, parameter behavior, and Excel export more complicated.
Sometimes They Are Exactly Right
A report may genuinely require separate data contexts or logic that is clearer in a subreport.
But Simpler Architecture Is Easier to Live With
When the same result can be produced cleanly without extra layers, we generally prefer the simpler design.
The client has to live with the report after we leave. Maintainability matters.