Sure there is nothing fundamentally wrong with buyables and nothing fundamentally wrong with gathering, but at Runescape's center it breaks the philosophy of RuneScape when OSRS gold you're able to just purchase through"slow" RuneScape skills (typically, these are gathering RuneScape skills right?).
I would assert that divination hardly even strayed from this course; it is exceedingly generous to call it a buyable RuneScape skill. There's a single buyable method in chaos energy and is not a noticeable xp growth in contrast to the meta methods, and of course CE is not readily obtained for the general public and most often entails dealing with extremely sketchy merchants. The whole allure of dividing RuneScape skills into these two (we'll ignore combat for today ) categories is that they allow RuneScape abilities to interface elegantly with another (recall back in the day?
Gathering RuneScape skills were generally regarded as"prestigious" because of the fact they were slow, grindy, and were the epitome of all RuneScape skilling. Say what you would like about how unappealing the previous approaches may be, but at its core that is just what MMORPGs are about lol. That is what MMOs have always been around, even though they may not be the most played game genre in this present day and age.
So, no, actually, I'd say that"fundamentally" it's wrong to unite collecting and buyables. Standalone RuneScape skills are fine (e.g. agility) but they are usually utility RuneScape skills. Imagine if you could just throw money at runite rocks and double the pace where you would usually obtain 99 mining. Could that be okay to most people? The closest equivalent to this is going Telos and purchasing keys with your gain to spin out a maximum cape... A quick look of the subreddit should inform you it is painfully evident how many gamers disagree with p2w-style MTX. Purchasing chronotes isn't as egregious but the ideas are almost indistinct.
The level is different, but the memory/energy relationship functions almost exactly like the artifact/material relationship. You get the main xp out of memories/artifacts. You want energies/materials to become xp from the memories/artifacts. You do not get enough energies/materials to cheap RS gold pay all your memories/artifacts, and therefore you have to buy energies/materials from other people to find max xp prices. Or, you may simply get energies/materials to sell to other people, or somewhere in between.