That's because they're probably ignorant about its unsafety and predictability. Also, some people never learn even if they get punished for it over and over again.
Not everyone is Leifang or Kokoro where they can just mash random buttons and pretend they're being "strategic" by using safe pokes. Some characters just have to rely on unsafe mix-ups for neutral pressure. Phase is one of them. It's her fastest mid poke and beats most shit in the game. Even being fully aware how unsafe it is, it's not a bad match-opener.
interesting points from everyone, i guess using this as a round opener is great against people who just luv to hit all the buttons. But against someone who'll actually block, or knows what the hell they're doing, probably not so much.
It's not a hard move to hit confirm with, if you don't mindlessly 6PPPPPPP and watch what happens you can keep yourself "safe" (if the opponent respects 6P's followups) and not do the second punch.
It works on those people too, provided you mix it up at least half the time. Which is exactly how all other moves that beat 99% of options in the game work. You could make the same argument for Hayabusa's headbutt, which forces a 50/50 on match start. Since that is literally the best his odds ever get in the neutral game, it's a perfectly valid option.