Does it matter?
To follow, if all divinations are by definition "information gathering," as far as Mind Blank is concerned, than the statement "information gathering by divination spells and effects" is redundant, and could be replaced by "divination spells and effects" without loss of meaning.
Since it was not written in such a way, we have before us three options:
1) The writer was being redundant, and knew he was doing so
2) The writer was being redundant, and didn't know he was doing so
3) The writer was not being redundant
In two out of three cases, the writer of the spell believed that there is a subset of divinations which are "information gathering" (such as locate person, locate object, status, divination, etc) and those which are not (among them, I suggest, are "sensory buffs," like see invisible and true seeing).