Personally, deep object ontologies make my eyes glaze over. Its not like these objects evolved in the wild and their ancestry is somehow interesting. Give me interface definitions any day. ECS is nicer for that.
From the article:
Using ECS
Nothing prevents you to use an ECS solution in Godot. In fact, I strongly suggest to check Andrea Catania's fantastic work on Godex, which aims to bring a high performance ECS pluggable implementation.
That paragraph really should've been the focus of the article, front and center - and from there an explanation on why it ain't built-in.
At the moment Godot is really only viable as a 2D engine, as it tends to bog down when used as a 3D game engine even though it has all but replaced the default Blender engine (their recommendation). So in order to get a viable 3D project, a user would have to use an experimental ECS version (no offense to the creators, they are working hard and I do have high hopes for this project. I'll most certainly be experimenting with it) using the C# version, which is still fairly new.
Now, the fact that a small group of devs can make an indy project/proof of concept with Blender and Godot, or students can make a group portfolio that is viable - these things are AWESOME. Granted. But it still comes out of a quasi Frankenseinian lab as they have chosen to go with OOP instead of ECS, it seems, even though a path does seem laid out before them.
P.S.
here's the link to the ECS project: