Blindness doesn't apply for other entities

If you apply the blindness effect to a random entity that is not a player, the effect is not applied.

 

Steps to Reproduce:

1. summon something
2. use "/effect give @e[type=!player] blindness 1000000 0 true"
3. use /gamemode spectator or use /spectate to spectate entities
4. the effet doesn't apply.