The need for a 'no flare' call may have been carried over from older systems - simplex monitored or some duplex autopilots with a 'bolt-on' flare mode.
I suspect that is true.
We still have a requirement to check the ILS QDM is correct at 350 feet - yet the data is frozen at 700 feet (data lock). So why delay the check so late until it is impossible to correct?
I suspect it is an old rule carried over from the days when we set the ILS QDM on an OBS next to the heading and speed knobs. It was easy to accidentally change the OBS, and the latest we could correct the error was 350 feet agl.