NIH is a cultural pillar. Even scripting layers are relatively split on if they're in-house or not. It's not uncommon to find both an in-house fork of Lua + a few other completely custom scripting engines all serving their own purpose.
If you need to do efficient path finding on random triangle geometry (as opposed to running A* on simple quad or hex grids) it quickly gets tricky.
What has undeniably declined is the traditional "10k US-$ commercial middleware". Today the options are either free and open source (which can be extremely high quality, like Jolt: https://github.com/jrouwe/JoltPhysics) or fully featured engines like Godot, Unity or UE - but little inbetween those "extremes".
I did mention this was changing in particular with physics engines. That being said, proprietary dependencies still reign supreme in places like audio engines. Something like OpenAL isn't really a replacement for FMOD or Wwise. I know those off-the-shelf engines roll their own replacements, but then they also roll their own pathfinding and navmesh generation as far as I know.
> Industry Standard - Recast powers AI navigation features in Unity, Unreal, Godot, O3DE and countless AAA and indie games and engines
I see the industry is of full double standards :)
It's not a terribly long list, it seems, even if it's non-exhaustive.
> I see the industry is of full double standards
Absolutely, and that's why it's so great. No two companies are going to look the same. The culture of the video games industry is a rather unique one that's kept its archipelago syndrome alive against all odds. It'll be a sad day if that ever changes.
There are entire classes (even genres) of video games that don't require substantial third-party library support, and it's frustrating to see that this seems to be more and more of a minority view as time goes on.