Not defening or anything. The current issue isn’t about hardware, is about reuse the old code which had several limitations. Like WoW most likely used the same code and had the same limitations.
While hardware improved, most of the game logic didn’t changed, thats their fault for overseeing that.
The science is that you can code a code with poor scalability and even with a supercomputer you would have bad performance when you try to scalate. Is a fundamental flaw on their arch design. Which is the root of most issues, that came from d2. Most of those issues were present on d2, just were less severe because didn’t had several folks in the same server at same time, they had several realms and their playerbase was really smaller.