No, there were never several unofficial libraries, one of which eventually won the popularity contest. There was always only one official. There is some barrier to add your project there, so might be that helped.
It's even more pronounced with the main Java competitor: .Net. They look at what approach won in Java ecosystem and go all in. For example there were multiple ORM tools competing, where Microsoft adopted the most popular one. So it's even easier choice there, well supported and maintained.
Agree, after I thought for more examples. Thanks, don't know why others downvote.
Besides consolidation point, I still think that "barrier to entry" point is still valid -- if it's more effort to even publish a library, its author is probably more committed already.
It's even more pronounced with the main Java competitor: .Net. They look at what approach won in Java ecosystem and go all in. For example there were multiple ORM tools competing, where Microsoft adopted the most popular one. So it's even easier choice there, well supported and maintained.