Not sure what is so depressing here. According to the chart, a total of nine listed networks died in 50+ years, this is actually astoundingly low.

And all IRC implementations are "interoperable" in the sense that a single client that implements the protocol can connect to any of them, this chart seems to be padding things a lot by calling every IRC server network a "chat service". A number of them also have or have had interconnects with each other in the past.