Unless you've done the study and can reliably say that the results are statistically significant in the scientific sense, then the statement that it's 'significantly less effective' doesn't hold.
Remote teaching can follow every pedagogical theory. Many teachers have been working really hard to apply thr concepts and adapt them, with no notice from the government. Many are now preparing so they another stint of remote teaching would be better still, and ready quickly.
If you've have qualified teacher status and practise delivering skills and knowledge to children on a daily basis, considering their prior learning, differentiating to scaffold and support, or stretch and challenge, take into consideration different learning styles, ask questions in the way you were trained to elicit deeper thinking and continue to provide feedback in a diagnostic way, the vast majority of children will still learn well and make progress.
My classroom doesn't allow space for me to remain 2m away from children at all times, so I'll likely catch (and pass on to thr other year groups) any germs they bring to school. With thirty two in there they can't all face away from each other. I can't circulate and pick up misconceptions in real time. I can't have personalised conversations with children about their learning across the whole classroom, disturbing others. The 'quarantine' of exercise books for 48 hours means my marking will not be as timely as it should, and more difficult for children to respond to.
I've been able to address all of those from my computer, but taking lots of time to communicate with each child, so going back isn't going to be necessarily better for learning.
I could attempt to have them in silence all day to speak to them. I could ask them to use their phones to photograph their work and email it to me while I hide behind my computer in thr corner of the room and type back to them. But I won't have time for everyone, and keeping track of them all will be difficult, when I'm running from room to room and sharing resources with other staff, in an environment that is categorically not covid secure.
I can't have a quiet conversation with a student who wants to talk about their problems at thr end or the lesson as I dash off. I can't see my tutor group to get ready for the day, as it's an unnecessary separate grouping. Assembly will be steamed to screens on different rooms.
Why would it be sensible to cram into one badly ventilated room for an hour at a time, with no masks or distance, before doinf the same withe four more groups in a day, to do what we've been doing from a distance even less effectively?