alt Hacker Newsit kinda sucks, but with the constraints it's at least understandable. they wanted an extremely lightweight language with a bytecode VM which could be ported to whatever MCUs in 2015, while also strictly limiting the functionality for battery usage reasons (and, uh, product segmentation/limiting third party access).
These days I'd say "sounds like wasm" but I guess 2015 was a bit before that took off.