I'm starting to think this wasn't connected to drugs/grow-op and this was more emotional/revenge/vigilante justice.
I don't think it was connected to the drugs/grow-up because now it's actually *exposed* it all when it was totally under the radar before all this.
If cartel, local competition, Kentucky boys were pissed off at this family or someone in the family the last thing they would do is perform such a grandiose murder to garner world news. The money would be gone, the plants would be gone, they'd draw attention/connections to themselves, they wouldn't need the headache or a trail leading back to them.
If it was other criminals they could easily just make them "disappear" without a trace without the grand shootout.
To me this has to be personal somehow within the connected families or community. Reasons come to mind: rejection from the business/not being included, humiliation (previous altercation with someone), a sexual assault/abuse and some vigilante justice, or just an "I'll show you" from a conflict.
JMO.