It largely depends what you mean by "works just fine", if all you want is "high throughput on a low latency link" then sure, whack up the buffer and throw it at

It largely depends what you mean by "works just fine", if all you want is "high throughput on a low latency link" then sure, whack up the buffer and throw it at the wall, it'll stick - but you can just as well use curl for that. To study higher end network stacks or more modern protocol dynamics, or cross network flows, the other tools are providing much better insights. The need for -P for basic tests is also telling and part of the problem: if the tool can't outpace a browser then even for these "basic cases" it's showing its inadequacy for the kinds of things the bulk of users care about even today, even with old protocols.