It's more or less what minimumsdk does, but there may be libraries that require you to bump the minimum.

For example, there are APIs that make feasible something that should be trivial (like autosizing a font based on size, the way it happens in iOS) but they are available from 8.0 so you cut out anything below that.

Or, we use BLE a lot and there are newer methods that makes our life easier but again are not available in older SDK versions