*4th wall. Star Wars was a simplistic good and evil story for 4-6. Only in 3 did palatine suggest embracing light & dark (& somewhat in 2 questioning why the jedi cant love).
& kylo suggests getting rid of light & dark then just goes back to dark because reasons.
And that's the entire poetic justice of Kylo Ren - the more he tries to kill the past(sever his connections like the Jedi were so fond of) the more it comes back to haunt him.
Are you kidding me?! Kylo never ever suggests getting rid of dark and light. He suggest getting rid of the PAST(order). He want's to dive into chaos/nihilism to escape his feelings.
Leaving the Jedi & Sith behind. Every time one side becomes more powerful the other rises to meet it. Kylo & Rey teaming up would merge the light & dark.