A modern smartphone has more RAM than most computer that people use to do actual work. I mean I see around a lot of people that uses computers with 4Gb of RAM, and the standard nowadays is 8Gb for Android phones. Even with disk space, nowadays a smartphone typically has 128Gb of rather fast SSD, a lot of people still uses computer with spinning disks.
Also are shared libraries all that used in Android? The part of the system that is written in native code is very small, it probably doesn't make all that sense to use shared libraries for that.
Smartphone memory is used for lots of things, e.g. modem carve-outs, graphics buffers, and page cache. The fraction left over for actual code is pretty small, especially on the smaller devices common in the developing world. Shared libraries are essential for using this memory efficiently.
Also are shared libraries all that used in Android? The part of the system that is written in native code is very small, it probably doesn't make all that sense to use shared libraries for that.