You can work on a specific set of data while any unnecessary information stays hidden and does not obstruct the process.
Tools that collect and transfer the problem determination artifacts, such as collection scripts, might run much slower if they have to transfer a lot of old unnecessary information.
When gathering contact information, only gather the demographic information you really need - asking for unnecessary information annoys people and may discourage them from signing up.
Asking for unnecessary information annoys people and may discourage them from signing up.