I'm an avid Linux user, completely unfamiliar with BSD. Could you shed some light on how it further removes abstractions? I don't mind trying it out by booting it from a usb
Totally agree. But I'm somewhat used to silly things about htop, like selecting a process to kill using the arrow keys, or a default refresh rate of less than 1 second.
Linux is a large ecosystem, supporting many different functions (embedded to some extent; desktop; server; supercomputer clusters, etc). For any one of these, the other 'stuff' represents cruft. The BSDs (I am partial to NetBSD) tend to give you a basic substrate of 'the system', and you add what you need via 'packages'. It's a different philosophy, but no less valid.
By not running hundreds of useless programs, I guess. If you launch htop inside OpenBSD, it'll fill half of your terminal, and the rest is empty.
The easiest way to try it is to install it on a virtual machine. You'll see that not much is needed to get to a point to launch firefox from an xterm.