That's why:
Player piloted Afflictor can delete a Paragon/Radiant with ease. A Tempest can't even remotely threaten either.
Technically, previous patch, but this still applies. Only taking a bit more time, phase ships got slower after all.
That's nice. I don't care what a player can do with them at or near the skill cap when the AI will be controlling the majority of your ships.
I think someone stated that they almost (or did) take down a paragon with a hound or something.
The AI was already a little rough with phase ships, and now giving one to the AI is basically throwing the ship away. The AI doesn't know what to do with it, so combat phase ships are utter trash as of 0.95.1a-RC5.
The AI flying a tempest is capable of much, much more than pretty much any frigate phase ship right now. A destroyer equivalent for Harbingers. A cruiser equivalent for Dooms. To cap it all off, people say their encounters with even the more powerful Ziggurat the AI uses when encountered in the story is now embarrassingly easy. I'd expect a capital class to rip it to shreds.
The devs nerfed phase ships out of viability. I don't even think I use them in my fleet anymore. Next patch will probably make them better.
It's funny, really, since in the lore they're utterly terrifying to fight. They're like stormtroopers. The most dangerous thing ever—Come on, really!