You have zero proof for this just chatting out your arseLol somali aristocrat's didn't want to wear the common and old wrapping garments so they picked up on the garments of aristocrat's they traded with. If this thobe off shoot is Somali culture then the common Somali people would have been wearing a lower standard version (made of cotton for example).
Are you okay in the head? You realise pre-industrial revolution literally every Nation had a top aristocratic class that wore lavish garments while the rest of the population dressed in rags?A garment that not even 1% of Somali society was wearing isn't going to be considered historical and cultural garment.
It wasn't until after industrialisation and mass production of all types of clothing that things only aristocrats wore like Suits became the mainstream for the lower class.
What people today call "cultural clothing" is just what the aristocrats used to wear.
Why should Somalis be any different.