No, I also never said anything about a default constructor. You have complete control over creating your items, you just have to do it at the right time.
What: Not using an object base class
Why: Using an object base class (commonly called BlockBase or ItemBase) is unnecessary and is an anti-pattern. There is already a BlockBase class, it’s the minecraft Block class. Making a class just to have its children inherit default implementations of methods goes against the OOP principle of Composition over Inheritance
Consequences: Using a class like this stops you from extending other classes and because lots of minecraft code uses instanceof checks to specially handle logic, you are likely to encounter weird and hard-to-fix bugs.
How: Instead of putting all your common logic in 1 class and extending it, extract the logic to utility methods. For example: Instead of calling setRegistryName, setTranslationKey, etc. inside your object base’s constructor, extract it to a helper method and call it on every object when you create it. In this example "setup" calls the above methods. registry.register(setup(new CustomItem(), "custom_item"));
You still have access to the registry name, just use the name you pass into the constructor