For the record (for anyone who is following the discussion), I have used the KendoUI/Knockout bindings and am comparing Knockout and React on equal ground. Nothing about the programming model would change if you just used straight HTML <input>s.
The main issue with Knockout here, is that the state of these apps (the JSON blob that changes as you click around) is not nice and rectangular and doesn't fit nicely into ko.observable and ko.observableArray. particularly the faceted search demo has tension where the lefthand facet checkboxes are grouped and have counts, but the top facet list is not grouped and don't have counts. In react, those are backed by the same state data, and the data is just regular nested javascript objects and arrays, you don't need to access the data through observables. You just use underscore to transform the data as you see fit.
The main issue with Knockout here, is that the state of these apps (the JSON blob that changes as you click around) is not nice and rectangular and doesn't fit nicely into ko.observable and ko.observableArray. particularly the faceted search demo has tension where the lefthand facet checkboxes are grouped and have counts, but the top facet list is not grouped and don't have counts. In react, those are backed by the same state data, and the data is just regular nested javascript objects and arrays, you don't need to access the data through observables. You just use underscore to transform the data as you see fit.