An abandoned house has a fridge with food in it. It has been there for at least six months. And it has spoilt. Flies are having a good time feasting upon the rotting organic matter. What or who observes it? The flies? The fungi? God? Are we arguing that a perception-less universe cannot exist?

The subject is never necessary in my opinion. There are only objects. The subject is accidental.

Truths are a process of a subject (a thing), and not a thing-in-itself.

A clear understanding of what exists and what are processes of existent things is necessary. From observation we can judge this. While this judgement is not perfect or complete it is the only method with which we have to judge. To chase any other method would be to deny the fact of this impossibly and be inauthentic to the reality.