The mandatory interface requirement for Simple Checks was removed quite some time ago. 

However, this requirement still exists when using host prototypes. 

How to reproduce:

1. Create a host prototype without an interface
2. Link the ICMP Ping template for this prototype
3. Wait for the LLD rule to be executed. 

Result:

LLD rule will be failed with the next error:

"Cannot link template(s) <template_name> to host <hostname> cannot find any interfaces on host"

Expected:

Newly created hosts from the host prototype, with simple checks on them.