We would rather help you choose correctly from seven useful things than confuse you with seventy similar bags.
Each of the seven has a job the others do not do: living soil, deep sustenance, recovery, protection, unlocking, structure, and one complete mix for people who would rather make one decision than seven. When two bags would do the same work, one of them does not belong in the range.
Seven is not a promise that Prahas will always have seven products. It is a promise that the range grows only when there is a real reason for another product to exist.