Soldered parts are prone to fractures in BGA solder balls which are more annoying and expensive to repair compared to cleaning up sockets and rubbing pads with a pencil eraser one in a while.
Socketed RAM modules have more solder joints than the alternative. The packages on your socketed RAM are attached to the module the same way they would be attached to the motherboard. BGA has been used across the board since DDR2.
Of all of the parts of your laptop to break and leave you without the availability of a replacement, your RAM is the least of your worries. Damage prone parts that are replaceable are already hard enough to find replacements for. And of all the parts on your mainboard to break, your i/o is going to be the likely culprit. And few laptops modularize those.
