Because 99% of the players of Minecraft are casual pussies who cant go 1 night without sleeping because they die in this oversimplified casual shitpile 200 times a night. So they complained and whined at Mojang about not being able to sleep. So in typical assbackwards thinking style they're known for, Mojang, instead of fixing the mechanics of the game, punished players who are actually good at videogames and who don't die in the easiest fucking game in the world by forcing them to sleep by fucking annoying them to death with swooping hard to hit Phantoms.
I don't have a problem with Drowned Zombies, but fuck casuals for "necessitating" Phantoms. Go be bad at overwatch or something, fuck.