Locked bootloader's are a manufacturer thing. Also, thought I read where the V20 got 8.0 recently.
General consensus is that rooting phones has become more passe with each new os version available.
Not to mention that rooting--
1. voids warranty
2. your phone becomes "third party". which means most of your device's usual support is kaput
No one is saying you shouldn't. It's your choice. There s a learning curve, and when you run into some problems, your only friend would be google and XDA