What happened in 2014 that spiked OSRS's playerbase? I'm curious.

I played a LOT of OSRS when it was first released, and even managed to get to the top of the crafting high scores and profit from crafting fury amulets. But the game was just turning into an RS3 clone with legacy combat, and a lot of the new content turned me off from the game (looking at you NMZ). Also the fact that everything had to be polled was really just inefficient. I felt like I could enjoy RS3 so I switched over and haven't looked back. I don't feel like your points about RS3 are misled. I haven't had any problems with just ignoring cosmetics, and I still enjoy the game because there is just so much content. The reason OSRS is able to survive like this is because a portion of the RS3 profits go to OSRS. OSRS has it good, they have no MTX and no cosmetic overrides, but the way they keep dumpstering on RS3 for having them even though they're directly benefiting from it is extremely hypocritical.

Runescape's changed, the internet changed, the wiki alone kills any way the game can be played as a "sandbox". RS3 has been around for 15 years, so the amount of content it has is overwhelming. You're right that the tutorial system could use a makeover, like freaking remove that stupid crater by lumbridge and make it look like it did before, but I feel like your opinion on cosmetic overrides is weak. Overall, the game is hardly dying. It might be different from 10 years ago when everyone was noobs, but that doesn't mean the game's gonna die.