Reply To: Why is it important to use the sculpt base mesh toggle?
Generally you always want to keep basemesh and sculpted data spatially in sync. Changes to the base mesh directly affect the sculpt, but changes to the sculpt do not affect the basemesh. So your multires sculpt data can become disjointed from the base like this gif shows:
Which can be a big problem, like if you wanted to export your base mesh to another 3D app and your sculpt data as a displacement map.
The Sculpt Base Mesh toggle allows us to make large proportional changes to both basemesh and hi-res sculpt data at the same time, keeping both in sync.