Nothing can be purely the opposite of anything. To cut right to the chase, if something is opposite something it inherently has at least one similarity to it’s opposite: they relate by be being opposite. Relation prevents true “anti-” states.
If that doesn’t convince you, let’s get fundamental: “anti-ness” is ephemeral or false per universal laws of conservation. I’ll use particle-anti-particle pairing to argue this. A particle will always have an anti-particle but opposition is equalized in the end. Any apparent opposition is due to energy gradients and flow of energy towards neutralization, giving the illusion of opposition due to our human-based and space-time-limited perspective.
Likewise, vacuum energy makes “virtual particles” of equal but opposite physical properties, just to have them cancel each other out. This is fundamental quantum flux in absence of ordinary matter ( a sort of inherent energy that is neutral at normal scales, but on quantum – or Planck – scales there is balanced but active fluctuation in the fields.)
Ultimately, if we saw the universe unfold and complete to it’s entropic conclusion, then we’d see neutralization, not opposition.