It's a mistake, and here's why
I've owned all OP's except the 2.
OP is very good to their customers, with the exception of a little model myopia (3,3T,5,5T) but updates have been up front, and timely. And for a 2~3 year model, quality is exceptional for US models.
So why complicate "all things OnePlus" by having a carrier weigh in on content and updates?
OP 5T notification light
With OxygenOS you can pick one of 8 colors for notifications and opt to turn on or off per app (e.g. you want SMS to flash, but not weather channel), but it is just one color. The review makes it sound like you can pick colors for various things: "There's also an LED indicator light, which can be set to blink specific colors for specific types of messages or other notifications."
In practice 3 of the color choices are "battery full, battery charging, battery low" and the 4th choice is "default notification."
to clarify- this is not like Cyanogen in the OP One where you had ...