[ppurka]

Having RAM slots that are user serviceable and having them soldered directly into the motherboard is besides the point.

If there is only one RAM slot (whether soldered-on or otherwise), then the total memory that can be supported is at most 16G.

[rayiner]

There are no DIMM slots at all on an MB or MBP motherboard. There are bare memory chips soldered in a dual channel configuration.