
It is there because the removal was priced as a felling job and grinding was quoted separately or declined — that is the usual reason, not an oversight or a crew cutting corners. Felling and grinding are genuinely different operations needing a different machine on site, which is why nearly every estimate itemizes them apart.
A cut stump at or above grade with the original root system intact below it. Over time: mushrooms or shelf fungi on the top and sides, bark separating from the wood, the surface going soft and punky, ants or beetles working the interior, and a sunken ring in the lawn as the roots break down. Plus a trip hazard and a mower you keep steering around.