No. It returns pixels. We need pixel density.
The biggest use of this is with text and UI.
I want my test to be, say, 0.5 inches high on all devices.
This is impossible to do without knowing PPI.
Which means that I have to pick a percent or pixel size.
If I pick a percent, say 2%, it would make the font 24 pixels high on a Nexus 7 which would be 0.11 inches high.
On a Nexus 5 it would result in 0.05 inches high text which is impossible to read and won't render well.
Pixel density is extremely common to use in mobile development.