what is recovery command's major purpose ？

[leafji]

I have one question about bulkload's direct load mode, that is :
when do direct mode write, if postgres happen system crash, we consider that bulkload bypass wal and write its own database file .
if this transaction not commit, data is not visible for other session. so why should do recovery command for this scenario before postgres do its system recovery jobs，is it necessary ?
Suppose if we do not do this jobs, what is the worst-case scenario ?