There never were good old days like that. Everyone is expected to have experience, in every area of life, including gaming. If you had no exp in mara and caused a wipe you still got a shitstorm. It depends on who you group with, and since today that's with more random people who don't care about manners, well, you'll get more hate.
That said, Marxman, while that's definitely true and I completely agree with you, being such player myself and usually "winging" the fights as they come with little knowledge on the upcoming fight except the necessary mechanics (shared healthpools, energy levels, whatnot), it's not how it works for more casual players. With progression like we've had, there usually aren't even vids or strats to look up even if we wanted to. But anyhow, a problem that many casuals (for lack of a better word!) have is their lack of understanding on how to analyze problems and/or improve. And in all honesty that's really not their main issue to begin with. A very big factor in those wipes is, well, standing in fire. While you may see the blatantly obvious frost orb even without having read about it and understand this is not a thing you want to stand in, the majority of players in fact doesn't see it, and if they do aren't adding 1+1=?? to come to the conclusion to not stand in it. Look at the plethora of Horridon threads for a glimmer of this.
I don't mean to be condescending, and sorry if I sound like that, but that is why the majority of guilds will require you to look up tactics: so you don't wipe the guild through sheer stupidity and unnecessary mistakes. Good progression guilds have shit like that covered, death by common fire isn't even a topic that gets discussed let alone is ever an issue. Which is why they don't need the vids, because that's all the vids can get you. Inexperienced raid leaders can get tactics on non cutting edge progression bosses, or bosses that got nerfed, like normal modes too, where most tactics is a Works For Everyone. Tactics at more cutting-edge progress are usually so composition-focused that you can't even get that from a vid.
Which is why top 100 guilds and common guilds that are the majority cannot be compared.