Because Intercalary meristems are found in the the stem part of the sugarcane in whole length.
Explanation:
As we have studied about meristem regions, that these are the regions found at the nodal areas which are able of cell division and growth. Intercalary meristem are present in the nodes of sugarcane stem which lead to the rapid increase in elongation of stem.
Intercalary meristem are located at the base of leaves and nodes that leads to the increase in length.
On the tip of sugarcane, apical or tip region meristem are found. When the tip region is removed, the presence of intercalary meristems play the role by facilitating the elongation of stems in sugarcane.
Please see attached image for better understanding.