It is recommend to use dummy node between Output of one XOR to input of another XOR, but why when it works fine ?

I have gone through https://docs.appian.com/suite/help/18.1/Looping_Process_Flow.html , as it says under gateways and logic : 

• When a looped flow enters an OR or an XOR gateway, the gateway pauses after the first instance token passes through – until all other incoming flows arrive.
• I didn't understand it ? can anyone please explain it bit elaborate? thank you