My first dead show was back in 1982. I saw a few dozen shows between '82 and '89, and saw the parking low scene transition immensely in the late 80's, especially following the release of Touch of Gray. Towards the end of the 80's the scene got larger and larger, and there were many, many more people that were starting to show up just for drugs, I also started seeing more fights at this time also, many more drunks than I saw previously, etc.. It was sad to see these changes occur, even camping out at venues started to get prohibited.
Of course, there are also the heads who followed the band in the 70's and complained how different the 80's were.
I've seen phish a few times over the past ten years or so. There is simply no comparison between the dead scene and phish scene. Im not saying one is better or one is worse, they are both just completely different.
There is, was, and never will be anything like a Grateful Dead concert.