- Cause when you erase something in Paint - the erased space gets white - like the Background - & whatever You erased Gets Invisible :) 

- And in Sketchpad it makes some Checkered Pattern instead of 'Cleaning the Space'! 😆⤵

🔷 Does it make Sense? 😁

- I'm sorry, but in My Opinion: Not Much! XD

( I tried to change it to Erase Like in Paint - but Either I can't do that - or It's Impossible here! )

*LOL XDDD