Unity's been killing itself with it's own fragmentation. Instead of upgrading existing systems, they've been replacing entire systems but never reaching a point of being able to deprecate/remove an old system.
So now there's 3 render pipelines, 3 UI systems, 3 physics systems, 2 input systems, and so on.
This makes it harder for new developers to get started, and it breaks a lot of the content on the Asset Store.
Just the HDRP/URP split alone is such a mess, with URP feeling like the second-class system and missing important features (while being the one designed to work on a wider range of hardware). But HDRP is the render pipeline used for shiny tech demos...
Yep, that's it. The engine used to be developer friendly, now it's downright hostile due to fragmentation. Half of it is deprecated, the other half is experimental and feels second class. They keep piling stuff up, and information is scattered. A modern project will have three of four different ways of adding libraries or third-party stuff. And the worst part: I might be totally wrong, because they might have completely changed everything since the last time I touched it.
Which is a bummer, given that since the XNA story, Microsoft has decided to outsource to Unity the whole "how to do 3D in .NET" story.
Given that the DirectX team is quite anti anything but C++, as shown by all attempts that eventually were killed (Managed Direct X, XNA), Unity's death would mean most shops would just move into C++.
While C++20 is quite nice, it would be a pity if such scenario would take place.
A lot of indie teams don't want to write c++.