Can be quite a bit buggier than stock, can be difficult or impossible to use some apps. You can lose some stock features sometimes. You can spend a lot of time debugging issues.
I don't want a different experience, I know you can install different Linux OSes on your phone but that's not what I use my phone for. Last I checked Ubuntu touch barely worked too.
What I do on my PC and what I do on my phone are different. Above all the most important feature of my phone is that it works reliably, not that I can tinker or install mods
Well Linux is an entire different OS which comes with its own benefits. Rooting makes it a lot more difficult to use apps that use safetynet so doing it because "why not" rather than for a specific benefit doesn't make sense to me
I had my note 8 for longer than security updates existed so I installed lineageOS on it, it got security updates but lost a ton of other features and became buggy and slow. Maybe with other phones the experience is better.
Different uses for a phone then I guess. To me my phone is an appliance like my washing machine. I want it to work when I need it to and be reliable.