-If you shove lane into the enemy tower over and over and get ganked by the enemy jungler repeatedly, it's YOUR fault for putting yourself in a prime position to be punished, not your jungler's fault for ganking less.
-If you continue to die to your lane opponent repeatedly and keep trying to kill them even though they have increasingly more gold than you, it's YOUR fault for doing so and not the fault of the "noob" jungler for failing to part the clouds like Elo Christ and saving your lane.
-If the jungler tries to help you out and the gank(s) fail because either the lane opponent is too slippery, too fed, or you and the jungler don't have the combined CC to get him reliably, the jungler can indeed go help other lanes for a while without being a "lul noob never helps pls report"
-If you're feeding your ass off to someone like Illaoi who can double kill the jungler as well as the top laner, it's not the jungler's fault they don't want to continue giving gold to someone who is crushing.
-If the jungler doesn't give mid blue buff because they are behind on gold or XP, need blue for themselves to jungle, because they need it to hit 6, or just because they want it, that doesn't make the jungler a trash can who needs to uninstall. Seriously. You can live without blue, and more than likely the jungler can then gank mid to help you.
-Finally, if the jungler is legitimately doing bad and just wants to catch up so they can be useful after laning phase, don't flame them for helping less.
I feel like 80% of players understand that flaming is wrong in any case, but there's a solid number of people who basically blame any game win or lose on the jungler, and especially with tensions being high and everyone trying to get placed in ranked people are being extremely vitriolic. Don't flame any role for not doing exactly what you want them to do, trying to be team captain will just tilt the person you're flaming and you'll probably lose.