People often use blocks a 'containers' for data items, as a way to visually organise a diagram. This isn't really what blocks are for, it's just a happy accident that you can use them as coloured backgrounds.
However it's Best Practise to not use 'decorative blocks' within the flow of the diagram. Blocks on the side used just for data items are inert and harmless, but when a block is part of a flow it is active and the potentially risks that exception handling does not work as the developer intended.