Maybe theres some benefit in adding a good (maybe better than whats there) strain. If you buy microorganisms for biotech I think they ( i forget the name) generally make sure its a good strain.
But there was very little information given with the product and it could have been made just with what they happened to have
In microbiology we tend to order strains of bacteria or fungi or whatever, based on the results we get/got with them. So it's not "them" making sure it's a good strain, it's the person who places the order.
But it's true that there are strains to pick from, one being onozuka R10, a strain if trichoderma that breaks down cellulose if memory serves me right. The extracts are widely used in food and paper processing.
In human cells it's a frigging patent mess though. There's a strain of cells used in cancer research (i think it's called HeLa) that was more or less accidentally donated to science after a diagnostic intervention. Those cells are sold for insane amounts of money and the family of the dead lady has never received a penny.
Mycology however, is a super young science and most products you buy can be considered "wildtype" in the sense that the spores are either collected from nature, or they're so many generations away from the original strain that they've evolved away from it. Fungi especially, can rearrange their genomes based on whatever they mate with, get infected with, or are exposed to. And fungi can mate with over 200 partners.
That isn't always a bad thing though. Because the more variability, the higher the chance there's something that sticks. That being said, there are companies out their with their own stock cell lines that produce reliable strains. Those are both labor expensive as well as costly, but they are absolutely reliable in the sense that they act as described.