You may have a point, but it’s probably not as bad as it’s sound. First, as already mentioned, same phenomenon occurs in OSS (as said by ChrisRackauckas above). Then, because it’s not so common (… but happens). But also, because I see this as an opportunity to experiment with new solutions, before maybe merging it to a more popular package. The same is done for Julia itself, where some experiments are first “externalized” before being brought into Base. So this may be more beneficial in the end.
But for the user that “just want a package”, this is understandably quite confusing (I had a bad experience the first time it tried to plot something, a few years ago). And there I think it is the maintainer’s responsibility to mention similar packages, in the same vein as exposed by jlapeyre above.