I still use a 2012 macbook, which was the last one where Apple graciously let you replace most of the parts including the RAM sticks yourself before soldering them to the logic board. According to official documentation this computer could have only been ordered with 2x2gb sticks, can only support an upgrade up to 2x4gb sticks, but here I am running 2x8gb sticks without having to do any fiddling, just plug and play. Unlike OP though, windows 10 over bootcamp is luckily able to pick up the 16gb just fine somehow.