"It does not share an API with Unix, it's object-oriented and not pipe-based"
This is false, although it's in line with BeOS / Haiku propaganda.
Here's an example of one of the classes from Be's "object-oriented" API: BStatable. BStatable is a class for getting at file metadata. It has methods like GetPermissions which return 32-bit integers with bitmasks in them that you can compare to some eerily named constants like S_IXOTH even though multi-user doesn't really work on BeOS (or Haiku).
This is hopefully already feeling very familiar if you know anything about Unix, and otherwise totally bizarre - but let's peel back the covers a bit. How is this BStatable "object" implemented? Oh here we are, there's a system call named "stat" which returns a big flat data structure just like in every Unix.
Now BStatable is an especially hilarious example because of its transparent naming, but this is what's going on throughout most of BeOS and thus Haiku too. Take something Unix systems did in the 1980s, smear another layer on top in C++ and say "Pay no attention to the man behind the curtain" in your best Oz voice. By throwing everything from code for handling joysticks to a class that represents a dialog box into the same library you can give the impression that this is a comprehensive solution, but it's really just a vast utility library, it's doing no more (and sometimes less) than Qt but without the benefit of being cross-platform.
It is no surprise that getting _developers_ to fall for this is harder than finding users who want to go along with the propaganda without knowing any specifics.
Haiku mostly deviates from BeOS in being _more_ like a modern Unix. You will see claims that this is just for "compatibility" but in practice most of the changes involved were _fixes_. Being more like Unix means being less _broken_.