Bloom's two-sigma problem is only tangentially related to your argument. What Bloom found was that one-on-one instruction using a very specific type of teaching

Bloom's two-sigma problem is only tangentially related to your argument. What Bloom found was that one-on-one instruction using a very specific type of teaching (Direct Instruction) coupled with mastery-based learning, results in some pretty spectacular gains (at least according to a few, rather underpowered studies). If anything, the two-sigma problem argues against in-person teaching. Mastery based learning requires that a student prove that they have mastered the current concept before they are allowed to move on to the next concept. That is much easier to do in an online setting, where each student can be presented with customized material, than it is to do in a class of 30-or-so bored undergraduates.