Ill tell you why I think they did. this mb7 comprises about 10% of cycling threads we see, prominent enough its not just your lfs offering it as a cycler.
they use it for sludge digestion mainly, aerobic heterotrophic bacteria in the mb7
and coincidentally, Dr Reef found that most bottled strains even the common cycling ones are mixed heterotroph strains that are similar
lastly, after dna sampling by aquabiomics we can see over time naturally selected species take over nitrification alongside plants and algae (Tarichas observation) regardless of the initial dose.
nobodys dna tested swabs in a few years old tank had any of the originally dosed bottle bac, community alternation had occurred.
we aren’t able to find a single recent example of a failed cycle/ someone’s two clowns didn’t live/ so in the end the lfs get good feedback on any strain they recommend. It’s us web nerds trying to find which strain is fastest that mb7 was deemed the slow turtle of the group.