> Gecko just wasn't designed to be embeddable in the first place.
This is untrue in the starkest sense. Please don't make stuff up and then present it as fact.
Embeddability was a major goal for Gecko at the outset. It's the reason for many of the architectural decisions that exist today (past the point where that goal has been abandoned).
I wouldn't say it was really hostility. But Gecko just wasn't designed to be embeddable in the first place. And they have millions of things to catch up at the time they ultimately decided they could only focus on a few things like Quantum and other things in Project Snappy. May be in the future.
Compared to Webkit the whole engine was designed as an embeddable engine from Day one.