NextStep adopted it but did not invent it. Once Apple acquired NextStep and released OS X they were the only major company supporting it and had defacto control over the language.
The complaint I have is with NSObject which can be blamed on Next Step. Although another comment pointed out I just didn’t know about a workaround.
There were two different major mutually-incompatible “flavors” of Objective-C (my first book on Objective-C covered both, and my first Objective-C programming was done on a NeXTcube), one of which originated at NeXT (NextStep was the OS that was NeXTs last major surviving product after they dropped hardware, not the company.)
The complaint I have is with NSObject which can be blamed on Next Step. Although another comment pointed out I just didn’t know about a workaround.