Because those gamers have realized the brilliant, rewarding nature of the game's difficulty. They actually have respect and understanding of why the developer designed it like that. It's frustrating for them to see other gamers essentially wanting to devalue the experience for themselves. It's the lesson that even small children get taught: “If you cheat, you'll only be cheating yourself.” It's funny how many grown adults just don't get that when it comes to this series.
The feeling of overcoming the challenge is what has resonated with so many people and positioned Souls in so many best ever lists. A player who just gives in and switches to easy mode will not find nearly as much satisfaction with the game, or form as deep an emotional connection with it. It's likely that the game would just become another forgettable hack-and-slash title on easy mode - just a safe, 'good' game, not the masterpiece many wrestled with and triumphantly defeated. I will hear many people now say: "hah, that means the game is nothing without its difficulty!" as if it's some sort of gotcha. But... yes, that just proves the point that the difficulty is an integral part of it. Every masterpiece ceases to be if you take away a critical part of the design.
This also reminds me of another thing which the haters and journalists often cry about: that the mantra of 'get gud' is demeaning. But actually looking at the words, it's backhanded encouragement. They aren't saying "gtfo of Souls", they are giving a command to stick with the game because they know it will ultimately pay off. Fans don't want you coming in demanding an easy mode, but what they do want is for you to succeed at beating the built-in difficult. Almost everyone will give advice, so the idea that the community is elitist is frankly crap. There are whole wikis devoted to the games which no one shames anyone for using. Hell, there are even community hint messages built into the game itself. This shared experience you get from everyone playing at the same level is by design, as Miyazaki keeps saying. One person will have a hard time, another person will have an easy time, so that person imparts advice like tactics and character builds, and - oh look, you now have a discussion going. Whereas you would not if the first person just switched to easy..
As for this idea of it being 'their only chance', that is such a ridiculous phrasing. You make it sound like this is some 'one chance to save the whales' student activism. As you say, people can choose to buy it or not, so i'm puzzled why someone who chooses not to buy a game would continue to fart into the wind about it when they aren't even invested in it. It's like screaming: "I WANT TO BUY YOUR GOOD GAME, BUT FIRST PLEASE CHANGE THE MAIN REASON WHY THE GAME'S GOOD". The series has been going since 2009, over something like 7 releases now. Since then, the director has repeated the same justifications for its design, ad nauseam, in dozens of interviews. If it hasn't changed already, it's not going to. And yet, every new From Software release, we get the same nagging, the same articles from the usual retards refusing to get it.. So I don't blame people for getting annoyed at this fucking dead argument, because I sure as hell am.