Scientific results can be strengthened by replication, but that's just one thing, and if that's all you do, then you end up with a science that does nothing but generate independent factoids.
On the other hand, robust science tends to look at a particular phenomenon from many different angles, and manages to connect multiple results together into a framework that can survive retracting individual studies without collapsing. This is how electromagnetism developed.
Sciences that are in the factoid phase are not necessarily junk. Discovery of a psychological "effect" is perfectly scientific and interesting. But some sciences have barely progressed beyond the factoid phase. And if those sciences are also plagued by irreproducibility, then they may embrace scientific methodology without producing a useful scientific knowledge base.