Is the ERP stock module not enough?
For many companies it is, for a while. If the ERP holds the quantity correctly and goods in and out are recorded properly, no separate system is needed.
Where it stops being enough: the ERP says there are 400 in stock but not which bin they are in, which batch they came from or what their expiry is. A warehouse cannot run without those three.
What does a warehouse system solve?
First, search time. If where goods sit is not recorded, picking rests on memory rather than information — and when that memory takes leave, the warehouse slows down.
Second, traceability. In food, chemicals and automotive, being unable to show where a batch came from and where it went is not inefficiency but a compliance problem.
Are handheld terminals essential?
Not technically, but decisive in practice. When the record is not taken on the floor as the goods are handled, the gap between the system and reality opens again.
The cause is not indiscipline but distance: when the person at the rack is not the person at the computer, every step in between risks losing the record.