Haverhill / Orange Line Transfer Help

Im trying to get from Logan to Reading. Google maps recommends taking the orange line to Malden to connect. Why not connect onto the Haverhill line at the north station or even at Oak Grove?

Im trying to get from Logan to Reading. Google maps recommends taking the orange line to Malden to connect. Why not connect onto the Haverhill line at the north station or even at Oak Grove?