Literally any launch of an MMO or expansion especially one as big as this you're going to very likely get issues. They can mitigate issues, such, but as PredatoryCatGirl says there's 2 main things that impact this, COVID19 and the worldwide semiconductor shortage, adding more servers will spread the load, but if they cannot upgrade and add more servers then that's beyond their control.

Then add the fact we got a huge influx of players migrating from WoW recently and they struggled to handle spreading out those loads where a whole data center had to had new registrations turned off.

Adding new servers to a data center would resolve that but sadly is the thing they cannot literally do right now.

And the things they can control they have been pretty good about. It sucks for sure. But there's lot of these rage threads now. I've been playing MMO's for a long time now...this feels...normal?

Unfortunately the massive spike in traffic is going to cause problems. It sucks, but the problems will even out.