Selectivity

Being selective on who we empathize with is a block to empathy.

Sometimes empathy is criticized as being selective.

It's like saying water is selective because there is none in a desert. It's a bit odd to criticize water for it not being in the desert.

Empathy is not inherently selective. Just like there are reasons that there is no water in the desert, such as a mountain range is blocking the moisture rich air from getting there, so to other factors that may block empathy.