Diamond 2, ex master tier jungler here chiming in.
Op, the sole reason for the jungler to exist is as a failsafe for laners, losing or winning. His one job is to babysit the lanes and provide map control as this is the role with the greatest flexibility and map influence over the course of the game.
If a jungler ganks your laner and that laner dies and all your jg did was farm in this time frame, guess what. Its you JGs fault for making a strategic misplay. He should have either been prepared to countergank or have ganked another lane at the exact same time to force an objective trade.
A laner who plays aggressively and always pushes, well, that's his own damn fault for making a tactical misplay. However, a good jungler recognizes this and is prepared to correct his laner's mistakes the instant the opposing team tries to punish him for it. A jungler who is unprepared to do this makes a strategic misplay.
If a jungler fails a gank because the laner lacked CC its the fault of both parties for failing the gank and making a tactical misplay. It could also be the laners fault for making a strategic misplay in champion select, but both players are at fault here.
If you have a laner who outright feeds his lane and dies non stop, you, as a jungler, made a strategic misplay in allowing him to feed uncontrollably without accomplishing anything else on the map. Either be aware of what the matchup is and why it is going south for that laner and be in a position to reset his lane after his first death or accomplish taking an objective somewhere else so that his poor play is less meaningful in a strategic sense. Again, fault is on both parties, but particularly the jungler for failing to be aware of the game state in a role that prioritized being aware of the game state.
A laner who throws away a lead after he was gifted one by the jungler has no one to blame but himself. This is the only correct portion of your OP so far. Laners, don't piss away leads you are gifted by a talented JG.
1v1 losses happen in lanes that get countered more often than anything. A good jg knows what the matchups are and which lanes require the most help the soonest. A jungler who allows a lane that is countered to suffer and does nothing to impact that lane in the first 5 minutes to 10 minutes of the game is a bad jungler who consistently makes strategic misplays and costs his teams games.
You seeing the big picture yet? You see the common theme in all this?
It's a team game that requires teamwork and guess who the most influential team member in a game is and has been for 6 straight seasons... Yah, you guessed it. The jungler. He has the most map influence and the greatest flexibility and needs to be aware of who to help when, why, where, and how. Bad junglers use the reasons you give as a crutch for their poor strategic choices. You should not reinforce the idea that this crutch is a good thing, jungling is already the most complicated and difficult role to play in the game without you offering very poor and fundamentally unsound advice.
No, its not the junglers fault for every last little thing. But it is the junglers fault for basically everything that happens in a game because he is the person who controls the pace of the game by default. Learn to jungle properly, learn to control the map properly, learn to make the proper strategic decisions, and learn to understand the matchups of your laners properly so that you are better able to make good strategic decisions.
Edit: Additionally, watch any high level player play jungle who is a jungle main. We will all do the same exact thing, we will all tell you the exact same thing. Gank, non stop, 24/7. That's how you are supposed to do it. Get your laners a lead so they are free in a strategic sense to apply their advantages elsewhere on the map. That is jungling in high elo 101. And yet you say its the wrong mindset... No. What you present as your argument is the wrong mindset. 100% of high level junglers will all say the same thing as I have said here. 100%. We all will say it. Because that's how to play the role in a fundamentally sound fashion. Pay attention to the map, go help the lanes, get them a lead, and then focus on controlling the map.