Wow, that is an impressive deadlift, and especially if you've only been lifting for three years. Nice job!
You are right that many people instinctually lift with rounded back and would benefit greatly from proper technique. But unfortunately perfect form doesn't completely eliminate risk of injury, it lowers it a lot of course, but it's still there. I have gotten compliments from experienced lifters on my lifting form and still blew out my back a few years ago, and other minor aches. I think there is always a risk involved in lifting heavy weights, never heard of anyone who has been lifting for years and never been injured. Many lifters seem to have some sort of injury that they need to work around (some can't do bench without adjusting for closer grip due to shoulder issues etc.)
That's the crazy thing, most of these guys have been through injuries the average person would consider permanently debilitating.
"Injury" is relative to your ability to recover. The strongest men specialize in recovery even more than lifting.
Prevention is always best, but injuries are practically inevitable.
I stopped doing deadlifts completely because my back kept getting injured, perhaps there was some underlying weakness that manifested itself or something. Or perhaps I did some damage early on when learning the lifts. Never seen a doctor because of it though.
Back in 2018 I quit deadlifting after the first four months of doing everything wrong, in my mind I was done with that lift and put a year into just doing Squats (still pulled something in my hip a few times, a different problem from back pain but probably still relevant to the Deadlift) then in late 2019 I tried deadlift again and found out it didn't kill me.
My best advice on the subject:
#1 Mistake is probably recovery time.
Deadlifting is abusive, it will hurt you every time, you need 10 days to fully recover even if everything went perfectly.
Most of the work in a good deadlift routine is not deadlifting.
Leading to...
#2 Mistake is thinking your body will naturally build stability at the same time as strength.
If you want to see a master example in hip movements go watch Martins Licis (2019 Worlds Strongest Man).
It's possible that some people actually use the compound lifts for primary strength building, but not many, you need to build each side of your body individually or you will become imbalanced and just topple over under weight.
(Ensuring balanced strength also applies to Bench.)
If I'm right about my current program then these two factors are probably why 99.999% of lifters quit.