This should be obvious, but the neckband isn’t there because it’s pretty. Instead, it exists to give manufacturers a place to stash all the electronics needed to make a Bluetooth headphone work.
With most wireless in-ears, all of that is typically put in an inline controller or stuffed in the earbuds themselves. When either of those are done poorly, it can throw off how the earphones balance their weight. They’ll look normal, but they’ll have a harder time staying comfortable.
Here, there’s no concern about space. As a result, the most obvious benefit is that there’s more room to implement a bigger battery. The 15-17 hours Jabra claims with the Halo Smart just isn’t feasible on a non-neckband pair.