Q1: Haven't NES Tetris players been reaching the kill screen for decades? Why does the article say that Blue Scuti did it first?
A1: In the past, "kill screen" was primarily referring to level 29 of NES Tetris. Blue Scuti was the first to reach a separate achievement (causing a game crash) on level 157, which reliable sources also separately refer to as a kill screen. Level 29 represents a substantial increase in difficulty, but it does not risk crashing the game.
Q2: Is crashing the game really beating the game?
A2: According to reliable sources, causing NES Tetris to crash on or after level 155 is akin to beating it, because the crash ends the game without the player "topping out" the board. Tetris typically ends with a cutscene of a rocket launch only after the player "loses" in this fashion.