Seeing post like this over and over is getting old. The game being harder back then is relative to the tools the player base had access to.
The game these days is a science, new tactics have been developed, more information is available, and the player base as a whole is much more well informed. Its like looking at something like fishing (IRL). Fundamentally fishing is still the same activity as it was 50 years ago. You go to a lake, you cast a line, you repeat till you catch something. But now there is new technology, fish finders, baits, line, tactics. Over the last 50 years fisherman have developed new techniques and technology and found things that work far better than what they had 50 years ago.
That is what has happened to classic. Yes it was difficult in 2004. The game then was every bit as difficult as the game is now. Is classic now as difficult as retail now? Nope. If i gave you all the fishing technology and tactics we have today back in 1920 would it have seemed much easier? Of course it would. This literally applies to everything in the world.
Over time everything that was once hard becomes easy. That is the way life works folks. Not just in WOW but in everything. Fifteen years from now people will look back on BFA and say "The game was so much harder then" and they wont be wrong, they will just be right and not understand why they are right.