I never implied that the Haiku developers would dislike these applications, so i'm not sure you being a Haiku developer has anything to do with your disagreement.
And yes, macOS users probably also tell you that they prefer macOS, though note that they also are often very loud about preferring software that takes advantage of their OS' features because this is why they use that OS.
The thing is, macOS has a much richer selection of software than Haiku has (and most likely, ever have) so macOS users at least can fall back to those. But if all you are going to use on Haiku is ported software that ignores native APIs then what is the point of using an OS with less hardware support and features?
The Linux desktop being fragmented doesn't mean much - your Qt application ported to Haiku will also work on KDE perfectly fine and chances are even if you limit your software selection to Qt-only applications, you'll still have more applications to work with. Though that fragmentation is really a poor description since there are standards you can rely on, like X11 - sure someone might be using Gnome or XFCE or Window Maker or i3 or whatever as their desktop, but applications do not target those environments, they target a lower level of the stack that is shared among these and making an application on XFCE doesn't mean it'll only run under XFCE.
So yeah, it might look fragmented, but unless you are some custom support worker that tries to navigate someone through the UI via phone, that isn't much of an issue in practice (and "in practice" is the important bit here because the reasons i've seen people put forth for having Qt/Java applications ported to Haiku and ignore Haiku's own APIs are all about practicality - which ignores the elephant in the room which is that if you care about practicality using Haiku in the first place wouldn't be a good choice anyway).