Based on their features and bug fixes in their releases and how it got progressively worse in terms of reliability/performance for the backend: I think it was c

Based on their features and bug fixes in their releases and how it got progressively worse in terms of reliability/performance for the backend: I think it was clear they made a decision to stop investing/prioritizing it and only tried to fix things when they realized they had their market share absolutely annihilated in no time flat. I can't imagine it was a "surprise" to anyone in management there but I'm not sure they expected resting on their laurels to result in major blowback as fast as it did.