If a planet strays too close to a black hole, tidal forces can tear it apart and accrete its matter into the black hole. Observing disruptions like this informs models of stellar and planetary dynamics.
It matters because it highlights the destructive potential of black holes in stellar neighborhoods.
It also provides extreme examples of gravity’s power.
A planet could be completely obliterated if captured by a black hole.
[ESA, esa.int]