Imo the biggest issue with this functional model (at least in React), is that it handles things like virtualization, async, etc. poorly. Which is kinda ironic, because in a true functional language, it'd be feasible to provide 'a world model' - that is act as if the entire state is always available, and let the engine decide when to evaluate pieces of code - without any effort from the part of the programmer.
Unfortunately when complex state transitions, async, and virtualization enters the discussion, the magic of React breaks, and you have to deal with all that, and also deal with how React's engine handles things under the hood.
Stuff like virtualization (if we're talking about stuff like virtualized lists) is hard not because of React, but because there just isn't any support for it in browsers. React doesn't really help here, but in my experience, it's usually the browser that starts choking on high element counts, not React.
Async is just difficult in general though. It's not really a surprise that most libraries/frameworks converged on similar designs.
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