Scan enough supplement labels and you'll notice a pattern: some list a single combined weight for several ingredients together, under a branded blend name.
When ingredients sit inside a blend, you know the total weight of the group but not how that weight is split between them. A blend could be mostly one cheap filler ingredient with a token amount of the active compound everyone's actually there for.
Research on any given botanical extract is tied to a specific dose. A disclosed milligram amount lets you actually compare a product against that research. A blend total doesn't.
A long ingredient list sounds impressive. A short list with every dose disclosed tells you more.