Can a rooted phone on stock OS be updated without wiping the data?

If so, how? The below is just personal experience relating to the titled question. I have a OnePlus 5T; it's my second smartphone, and just as I'd always planned to do with my second phone, I rooted it. The benefits far outweigh the drawbacks, except that I can't provide objective feedback on apps I use on it. At one stage I hadn't updated for half a year when I finally made an attempt. I was one OOS 5.1.1. It was recommended that I update to 5.1.4 then move up from there. As though some magic happened, while I was downloading the roms to my laptop, my phone DLed & updated to 5.1.4, then 5.1.7, without wiping any of my data. I then flashed Codemasters TWRP, installed Magisk, and the rest was history. The magic didn't repeat itself however. I tried to flash the rom through Codemasters as well as stock TWRP (if this sounds stupid it's because I don't really understand this all that well), but the update wouldn't take. Then again, seemingly magically, it took, but it took all my installed apps and personal data with it. And here I am again, with an update notification haunting me.