Salient points. I said of how I walked up Mill Lane from West Derby Village (about 400 metres) at about 1pm (they didn't even set off from Allerton until 2.30pm) and already both sides of the road were crammed with parked cars meaning you had to walk mostly in the road with moving traffic. There should have been a 1-mile parking exclusion zone from the route. The central reservation of Queen's Drive was crammed with cars too - something I never saw even in 2019.
There was officially 850k in 2019, and it's no exaggeration to say this was about 50% more at least. Some estimates say 1.5m (that may be a bit inflated), but the police said they were expecting at least 1m and that's easily what we got, so the crowd numbers didn't take them by surprise - or shouldn't have.
I'll make the point again though that it was leaving the parade that was - in my experience- the dicey bit, mostly caused when thousands of people try to cram down roads when parked cars are hemming you in and there's hardly any pavement to walk on. Just imagine the crowds coming out of a cup final and Wembley Way had parked cars all along the sides, and some dickheads were trying to edge through the crowds beeping their horns. Then multiply that by 10 miles.
Some are suggesting holding the next celebration at a venue, as they did in the 70s when they used to hold them on St George's plateau outside the library, but we are now talking over a million, not just a couple of hundred thousand. Considering over 1m were on the streets, the number of other incidents is negligible, but that said, I can well imagine there were several more confrontations between vehicles and fans that didn't escalate into what happened on Dale St - but could have been worse. I can't think of anywhere in Merseyside, even Sefton Park, where you could get a million people into. And the traffic and pedestrian controls would be even more onerous.