I attuned Hammerhead played at least 4 onslaughts a day for a whole week got zero shiny hammerhead, so far this week I’m on blast furnace same result # drop rates are -blam!-
Let me help connect the dots here: When the good weapons came along that people actually wanted, the drop chances decreased drastically. Consequently, people play more.
At the beginning, I got so many shiny weapons and I literally only got what I had attuned to. Now, curiously, I get zero shiny weapons and only like 60% of my drops are what I actually attuned to.
They tease you and show you how much fun it is to get all that stuff and when it comes to what you actually want, they nerf the drops so that you have to grind like a maniac.
Edit: Same strategy as ever. They cannot fathom that people actually play the game because they like it. They feel they have to force us into certain activities to make sure our playtime is up. Unfortunately, this whole strategy keeps backfiring.