Think one huge problem is Julia attracts a grad school crowd. The developers of a lot of packages graduate and then get python jobs. Then they have no time to maintain these libraries and they atrophy. Maybe someone decides to build a new package for the same thing – to get it to work in the contemporary Julia ecosystem – and with this, the process begins anew
This fills the ecosystem with many useful packages with a bus factor of 1
Then if you add in the fact that many packages change their API dramatically year to year, you end up with a toolkit where your wrench might not work tomorrow and your screwdriver might be missing by christmas