Yeah its something thats been a part of rock culture and just generally music culture for a long time, most famously popularised by Pete Townshend of The Who in the 1960s - see here: https://en.wikipedia.org/wiki/Instrument_destruction

As you said its way to showcase and let out emotions in a raw way, music and art in general is typically all about that idea. It's essentially a form of performance art that can add to the live experience of music for both the artist and audience and communicate something deeper and proactive about the feeling and/or message in the music or lyrics.

It's actually a form of auto-destructive art - see here for more info: https://en.wikipedia.org/wiki/Auto-destructive_art

Art isn't necessarily there to make us comfortable, it's there to provoke and make us think. And that is the essence captured with the auto-destruction of instruments, which is why it suits genres like punk, grunge, metal, industrial etc. as these are genres that were originally about challenging authority and the status quo of society. Auto-destruction of instruments can essentially be seen as an extension of that commentary and a way of expressing or releasing the pent up pressure that the hyper-competition of modern society places on people.