Well yes you are absolutely correct from a materialist standpoint. If you limit reality to material things, then truths are limited to material knowledge. Emergent properties such as subjective experience, society/culture, and ultimately meaning and meaningfulness are excluded from what is considered reality and truth, except for their material correlates. And this is why philosophers moved on from materialism because, while highly fruitful, it was ultimately insufficient in capturing all forms of knowledge.

I prefer a pragmatic blend of constructivist realism.