I think that with the exception of the kernel being a layer on top of MS-DOS (but that would be comparing with Linux not with KDE), Win9x was better technically than KDE1.

For example I do not think to this day there is anything tech-wise like COM with all of its related tech like OLE (which allows documents to embed objects exposed by other applications which themselves can run in 'embedded mode' to edit said embedded objects), ActiveX (which in a similar way allows applications to make use of reusable controls that can describe themselves), Automation (which allows applications to expose scriptable interfaces that can be called by any other application), Active Scripting (which allows applications to embed scripting languages which themselves are registered with the system so that, e.g., you can install a scripting engine for Python which then can be used to script any application that uses Active Scripting even if that application has no idea about Python) and a bunch of other things.

(note that DBus does provide the 'expose interfaces' part, but it is only about that whereas COM is a more generic technology that was used for all of the above)

What you're describing for a "dbus but for ui" is one of the core KDE technologies still in use today named KPart [0][1].

[0] https://techbase.kde.org/Development/Tutorials/Using_KParts

[1] https://en.wikipedia.org/wiki/KDE_Platform_4#KParts

Yeah i know about KParts, however KParts is more limited and the tech is only about KParts whereas COM is used for a lot of things, including even stuff unrelated to the GUI (e.g. Active Scripting). In addition COM defines a binary interface for accessing objects that can be supported by any programming language that can support structs and pointers whereas KParts is only for C++.

Windows 9x was a single user operating system; Linux and KDE/GNOME were and are not. Windows 9x is an absolute security nightmare, including ActiveX. Therefore, the comparison is moot (though ironically enough, X is also a security nightmare).

ActiveX is still available on Windows 10, it has nothing to do with security aside from being shoved into IE4 as a way for Microsoft to lock the web into Wintel back when Java's crossplatform-ness was seen as threatening to their desktop dominance - and thus gaining a bad name because it really wasn't designed for such a use.

ActiveX is just a standardized way to embed controls, in practice it isn't any difference than any desktop application that has support for plugins nor any less (or more) safer than that. COM in general is just a standardized form of a plugin system with a bunch of predefined interfaces (or binary protocols if you want) for applications that weren't written with each other in mind to still be able to work together and share functionality.