Why ST_Intersection from Postgis returns multilinestring for self-intersecting linestrings?

Question

I am trying on PostgreSQL with the extension Postgis to get the geometry of a gps_trace that intersects a box, then i want to get one linestring for each distinct part of the trace in the box. In the following example with 1 trace and 1 box , that would mean ST_intersection returns me a multilinestring with 2 linestrings inside, so that i can extract each of them with ST_Dump()

The geometries are in epsg 4326, I use the request SELECT ST_Intersection(gps_traces.geom, grid.box) FROM gps_traces, grid

But as a result, i get a multilestring with 34 geometries inside. After zooming a little, i discovered that when the line self-intersects, it seems to consider and register each part as a separate linestring although at the beginning, the trace was a linestring in one go.

I am extremely surprised of this behavior, and didn't find any documentation on the subject nor topics that talked about it, so i'm asking here how is build the geometry resulting from an intersection and why I get this behavior ?

This is the first time i get to use stackoverflow, so I apologize if some elements are missing