There are reasons why people debate it

1: You do know that the ACTUAL plot was that Marceline was fucking with Finn just to fuck around

Marceline’s entire personality was being a prankster at that point in time, so of course that’s what they were doing

IN FACT, Bubbline as a more seriously implied thing only started in What Was Missing and that was mostly fan pandering

2: Bubbline has never officially been canon. So while implied, it is not officially a thing

I’m honestly sick of Bubbline, because their personalities honestly wouldn’t work in a show relationship.

And because Finnceline is my otp and I refuse to accept Bubbline