Most seem to agree that NeXTSTEP/macOS/iOS wouldn't have succeeded without Objective-C. So much of the functionality that made it stand out was predicated on Objective-C's somewhat unique programming model.

Of course, it's all just 1s and 0s at the end of the day. You can ultimately accomplish the same in any language. But the design of the language does shape the way developers end up thinking about the problems. If NeXT had used, say, C++ instead, it is unlikely that the people involved would have ever come to recognize the same possibilities.