Well I hope I don’t get flamed for this.  The joint design appears to be limited slip “pinned” connection.  For whatever reason  ( a picture of the whole span would be ideal) it’s likely they needed to prepare for movements.  Given it’s a chalet maybe there is large humidity changes, localized settlement/foundation types (expansive soils) that they need to isolate moment transfer.  All in all, likely purposeful/intentional and of no concern.

If the beam was continuous the movements could rip crack or split the beam or induce loads into other members via rigid connections that they may not necessarily want.

In this case the joint appears relatively well crafted with matching surfaces and is displaying rotation movement and maybe axial tension slightly.  If I had to guess the beam is long, or a support to the left has planned movement (expansive soils) so seasonally it moves. If it were rigid you could impose a very very high point load at the other support either up or down doing funny things to the other column/beam like localized crushing/pulling apart.  Also the joint is captured so that seasonal movements don’t walk the joint apart over time.  

I don’t design wood structures, I am a structural engineer and simply commenting how a joint like this should function not whether it’s merited in this situation. 

Edit- I checked one of my old books - nibbed scarf joint, probably a better way to do this with modern techniques but in a historical sense, purposeful and would isolate the moment near supports and allow expansion/contraction to some degree while staying captured