I think the reason it works (I not try it though) is that in the above example, account2 is getting his raf from account3.

If you did only the Main and Account2 in the above example it probably would not work. But when you toss in account3 etc. then it works.

This is kinda interesting as then:

Main - Account2 - Account3
Main - Account4 -Account5

works, whereas

Main-Account2
Main-Account3
Main-Account4
Main-Account5

Does not work, for instance boosting.