I need some guidance in understanding what the virtue is in using
calcified seaweed in the garden.
I found the following features in a web search:

What it does: Breaks down heavy clay soils.
Increases bacterial activity in soil.
Conditions lawns.
Benefits: Improves soil structure.
Raises pH level in acid soils.
Helps prevent calcium & magnesium deficiency.
Can be used on: Heavy clay soils. Lawns.

Is there any item amongst those claims which are not met by using lime
at a much smaller cost?

Franz