Why a batch code starts at the shelf
Supplier lot numbers are not unique, not consistent and not yours. Deriving the batch code from the storage location fixes all three problems at once.
The supplier lot number is the wrong identifier
Two suppliers will happily ship you a lot numbered 220314. One writes it on the bottle, the other prints it on the carton and nowhere else. A third changes format between orders. None of them coordinates with you.
If the supplier lot is your primary key, your inventory inherits every one of those decisions. You get collisions, you get unreadable handwriting transcribed three different ways, and you get a search that returns two chemicals sitting in two different labs.
What Labnize does instead
A batch code is generated when the lot is put away, and it is derived from the storage location it goes into. The code is unique inside your organisation by construction, it is short enough to read off a label, and it encodes something a human can act on: where the bottle is.
The supplier lot is still recorded on the batch. It is just not the thing the rest of the system hangs off.
What it buys you at audit time
An auditor asks which batch went into a given analyze. The answer is a code, and that code says which shelf to walk to. There is no lookup table between the identifier the system knows and the object in the room.
It also makes the barcode useful. Scanning a label from a phone resolves to one batch, and the movement you record lands on the right lot without anyone typing a number.