Before Chapter 1044, people had no idea that Luffy will have one of the most powerful devil fruits in the series.
The Hito Hito no Mi, Model: Nika is the only devil fruit power that the World Government wanted to erase from the entire history. It allows the user to transform into the legendary “Sun God” Nika.
So we learned that Luffy has this legendary devil fruit ability that once Joy Boy had. This devil fruit was so powerful that it’s nearly a Toon Force ability that gives Luffy enough freedom to do almost anything he wants.
So who can counter this power? Darkness!
Sun vs Darkness concept was already highlighted in Blackbeard’s previous battle, where Ace probably used his Logia Awakening via Entei and covered the half of the island with his fire, that his ability looked like an island sized Sun:
Basically, before Chapter 1044, people were still saying things like Luffy’s Haki is more important, not his devil fruit ability. But Oda proved these people wrong. Post-1044 One Piece gives the main character one of the most powerful devil fruit abilities, with the concept of being the Sun God.
Luffy has now the ability to do almost anything the he wants, with more freedom and more power once its power has awakened. And Blackbeard is the only character who can counter this freedom and power, with its darkness that can turn everything to nothing.
It makes so much sense that Blackbeard specifically searched for Darkness Logia, when there are also other powerful Logia abilities in One Piece. It was probably for countering an absurd and a very powerful Toon Force-like ability.