It is not completely true.
If the metadata is known ahead of time, you can create an ipfs folder with the filenames being the id as per the ERC1155 rules
if metadata is to be provided as part of a minting process, you can as @abcoathup mentioned implement the uri function yourself or emit the URI event. if you use uri you ll need to store the ipfs hash but can use folder to do so in batch (one hash per batch). This is how we do it for https://sandbox.game