Explain why DI fails sometimes and how to fix this (#20010)

docs/guide/concept-di-container.md

@@ -396,6 +396,18 @@ class HotelController extends Controller
 }
 ``` 
 
+Note that not all core code supports DI due to performance concerns. You can add support if needed by overriding
+the method responsible for instantiating the class and making sure it uses [[Yii::createObject()]].
+
+For example, you can add DI support to [[yii\db\ActiveRecord]] models by overriding the `instantiate()` method:
+
+```php
+public static function instantiate($row)
+{
+    return Yii::createObject(static::class);
+}
+```
+
 Advanced Practical Usage <span id="advanced-practical-usage"></span>
 ---------------