What is missing in the 'live input followed by response' model of teaching that online learning favours is all the incidental, responsive teaching that happens in the classroom.
So a typical 'classroom' lesson would nominally have the same 'input' as online, but as a teacher you are constantly scanning the classroom - who is looking puzzled? Who has a question? Do I need to go faster / slower?
Then there would be some interactive practice of what is being taught - children might try a sentence on a whiteboard or do a couple of calculations and show their answers; the teacher might scribe a few sentences following children's suggestions; there might be some questions and answers; children might work in pairs or groups to generate ideas.
Then children would do the task - again nominally the same task as set online - but there would be much more interaction - let's check the answer to the first question; I can see that everyone's finding number 6 tricky, let's have a go together; read your story opening to your partner and get some feedback from them; remember the spelling of homophones. There would also be 1:1 or small group support, either planned or reactive.
There would also be some kind of wrap up - sharing of work done, checking answers and finding any that caused particular problems, checking against objectives.
Online learning can replicate the 'formal' stage of the teaching process, but can't replicate the 'informal' teaching that makes up the majority of the time in each lesson.