From the Guide to Advancement 2015:
Teaching skills necessitates a "hands-on interactive experience", frequently "with personal coaching and guidance". Requiring each scout to schedule and complete a personal meeting with a counselor forces them "to take responsibility for their own full participation. If they show up to their meeting, and don't know their material, or are unable to demonstrate or show, or ... this is no different than how things work in the best of situations
Separating the group instruction from their personal meeting with a counselor is no different than a scout learning the information for any of the citizenship badges in their government classes, attending a city council meeting with their troop, attending one of the US mints as part of a school trip, or whatever - it's a tool for them to learn them to learn the skills and knowledge necessary for completing the badge - nothing more, nothing less.
This model can - and already should be - used for completing merit badges at summer camp. At the end of the camp week, your counselors already should be having each scout individually show, demonstrate, explain, etc., bringing in their targets from the rifle range, or notes from EnviroSci, etc for a personal review of their efforts in completing the requirements. Will this model lead to more partials? Mmm.... probably. But... - I don't see this as a problem (compared to scouts that are awarded a badge for attending, as is frequently currently done). What is more likely, is that you will have a scout that has a signed blue card from a scoutmaster, that hasn't been signed off for anything because they haven't taken the initiative to meet with a counselor.