The use of C++ with inheritance based OOP was a huge technical limitation for BeOS at the time, because C++'s virtual method tables resulted in very brittle ABIs. Just about any changes to the virtual method definitions in a base class (even as simple as adding a new method!) could break code compiled against the old version. BeOS had all sorts of "placeholder for future function" nonsense in their headers to try to work around this, but it was very ugly.

This wasn't an insurmountable problem, because eventually it could have been solved with some sort of C++ aware dynamic linker. But at the very least it would mean an ugly ABI-breaking change at some point requiring all apps to be recompiled.

Objective C was quite different from the start because it's "message send" mechanism shifted virtual call resolution to runtime, making the whole programming environment more dynamic. Crucially, as long as function names don't change, old compiled apps can basically keep working forever.