I'm specifically saying it's NOT just that the player base has changed, demographically. Demographics do NOT account for the likes of the complex comparative changes in personal attitudes toward gaming you're describing. They would not be used to delineate by time spent bankstanding vs skilling. Now you are the one getting into semantics. A 12-year-old boy who plays RS for 3 hours a day is part of the same relevant demographic in 2019 as he was in 2005. And again, I'm not saying that's the average OSRS player. I'm saying if those two boys, being part of the same demo, will nonetheless play with different degrees of efficiency, that's proof it's not only the demo that has changed.

Efficient players drive efficiency updates but the reverse is also undoubtedly true. Players who aren't especially geared toward efficient play, who might have been perfectly happy to hang out in Varrock all day doing individual trades, will still take advantage of conveniences offered them, and the effect is the same. There's no disputing that.

It's clear how invested you are on pinning the changes described in the OP to one thing going one way. It's equally clear there are in fact multiple interconnected causes. This is over. Address your over-eagerness to correct people on your own time.