This is what you wrote…"no bearing on other aircraft means it is not speed for spacing or sequencing. Some of that…though somewhat non-sensical already is in MSFS. When you get instructions to maintain speed at or below xyz.
I have never heard ATC remind an aircrew of the 250kts restriction below 10000ft…I did hear them tell a flight crew to call a number after landing and mention that the speed restriction is in effect.