I am not saying Classic was bad, or that people are playing it out of spite. So don't try putting words in my mouth.
I am just saying people went back to Classic not because it was better, but because of nostalgia. You can even farm a lot right now for materials for flasks and foods and whatever else, but as the video clearly shows...it's not something people necessarily care about doing. Like we have CLEARLY more difficult raids now mechanically than we had back then, but because we've had nearly 20 years of experience, it feels like the old stuff was more difficult.
Here's another way to think about it.
You are just learning about multiplication and then division. I mean holy shit those were hard concepts to wrap your head around! 20 years later you are an engineer and you eat some kind of 5D chess quantum maths for breakfast and pick your teeth with multiplication and division.
Now this minute for you, multiplication and division isn't something you even need to remotely think about because it's so easy, but it was super hard 20 years ago. Literally nothing changed about the thing that was so hard or easy, it was just your own personal experiences changed.
It's the same thing with raiding. Back in classic, we were ALL absolute morons compared to our raiding selves of today. But for some reason that nostalgia boner is raging and makes it seem as if all the stuff we experienced when it was brand new was when it was all better and harder and we believe it will be the same. So we go back, get into the same routines and all that...and turns out it's just not harder because it CAN'T be harder for us.
But back to consumables. It wasn't just running out for a small amount of time to get buffed in order to raid for 3 hours or so. It was needing to go to certain places like Dire Maul for a specific buff. And then you needed either to BE an herbalist or HAVE an herbalist alt (or have people in guild dedicated to guild farming). We definitely weren't made of gold back then either, so it's unrealistic to believe every raider was able to just buy everything they needed for a quick boost.