You are right. The architecture is just creating burdens and frictions to sustain the business if mostly relies on freemium user expansion. This is especially attractive to VC backed companies as they sometimes are judged by their growth when they are pre-revenue. And growth with free users is like a poisonous apple, that looks appealing but only accelerate the burning of your cash pile. To the point that it's afraid of charge money that may impact their main growth metrics.

I do believe apps like ReadWise that charges a subscription will have a more likelihood of surviving. Or Omnivore if it's less aggressive in expanding to compute-heavy features without charging.

My main point is, this is a category that's better served by local-first architecture, on Apple ecosystem, you also have the added benefit of having icloud sync for free.