I experienced a similar thing when I helped a friend install LineageOS on their bootlooped Android phone.
Apparently, this process would have been 10x easier if they had switched on "OEM unlocking" in the Developer Options setting (which you can't do from the boot menu, recovery menu or via adb), which is off by default for a very stupid reason. We were successful in the end, but it was a LOT of hassle.
So, when you switch on "OEM unlocking", you get a warning that it's "for protection against thieves". Like, a thief would steal your phone and it's encrypted and locked, but because "OEM unlocking" is off they can't simply wipe it and reinstall to re-sell, or something. So to them it's a brick and therefore they wouldn't have stolen your phone I guess. Except if they spend some effort they can totally cleanly reinstall the thing, it just takes more steps.
Maybe I'm missing some part here about how this "OEM unlocking" option supposedly protects against theft, but for me it was a simple sum. Number of times my phone got stuck in a boot loop: 3, number of times my phone got stolen: 0. So I set that to unlocked, now I'll have an easier time if I ever mess up my phone again.
The only real reason I can think of is that they WANT your phone to stay bricked/bootlooped when it's bricked, and be unable to fix and repair it. It has nothing to do with theft, it's just a way to make sure the device stays disabled when it's disabled, and to make you buy another new phone.
Additionally, I got nothing but happy comments about LineageOS from my friend. You can really tell in the feel of the entire system the difference between what it means to be a user (normal software) or to be the product (like in Android or any of the Google/Facebook/Apple systems). Just by what options you're given and the fact that applications actually behave at your service instead of nagging you while you're trying to accomplish a task. I'm not really happy about how Android 9 is running on my moto-g6, so I think I'm gonna make that switch soon as well. You don't even need to root the phone to do this, but it's a choice (I think I'm going to root it though).