I view ‘extreme’ Minimalism as branding or a deliberate way to differentiate what would have been just ‘minimalist lifestyle’ 10 or so years ago against what is a heavily commercialised trend now.
The benefits are basically what is normally espoused about a minimalist life: clarity, mindful living, better financial management, flow, agility, and peacefulness.
It is a mindset largely. I own more a backpacks worth of stuff, although what I own is valued, used, and maintainable.
To quote Francine Jay:
In general, all the “things” in my life can be replaced; and in some cases, I may not even bother to replace them.