Why not inherit gyro sensor from PX4Gyroscope(class) but declare it inside?

[charles-lyc]

eg. class L3GD20 : public device::SPI, public I2CSPIDriver
There is a general gyro struct inside like :
PX4Gyroscope _px4_gyro;

so why not inherit from it like this:
class L3GD20 : public device::SPI, public I2CSPIDriver, public PX4Gyroscope