In real life we all "spread our things all over the house" to keep them in order.
Exactly. And the point of spreading files all over the directory tree (not filesystem) is to be able to easily:
- split the tree into several filesystems that have different properties such as size, speed, availability when the network is up, etc. - make part of the tree read only (to protect it from some problems) - make part of the tree shared between computers - and some parts shared between computers of different cpu architectures
For example it should be possible to make /usr read only and share /usr/share between different cpu architectures.