In Fall of 2006, Jagex introduced skill capes. Some vocal higher level players had been asking for "recognition" of their status for a long time - despite the fame of the high scores page.
What were the results?
In a few months many had stopped wearing their capes due to "noobs" constantly asking 'do emote pl0x!' The 99'ers became vexed by the repeated questions. It had become annoying, not flattering. Publicity has a price. (The fact is, if you have achieved something good, you already Know, and you can feel the satisfaction in your heart. Accolades from others are a bit nice, but they aren't the reason you did it in the first place.)
Other players, previously uninterested in grinding to 99, decided they wanted a cape, too. However, many also realised that getting a 99 means buying materials, which is the usual way for a 99er to skill beyond a certain point. (I'm not sure how much time it would take for one player to accumulate 13M xp worth of raw material on his/her own. Instant gratification is much better!)
It is acknowledged that the 'easiest' capes to buy are Fletching, Firemaking, and Cooking. Crafting comes along behind. (However, skills like woodcutting, fishing, mining, and thieving can't be bought - they require a genuine personal investment of time.)
So, players with stacks of money and a thirst for capes went to Falador and started buying raw materials. The prices for logs, raw fish, dragonhides, herbs, and seconds began to climb due to this demand. At the same time, the values of finished products (cooked fish, potions, etc.) began to decrease.
Around spring 2007 Jagex had a noticeable surge of kicking gold farming bots from the game. Overall, this was a Good Thing - the bots bothered anyone trying to skill in the same place, and their flood of raw materials had driven prices down horrendously. This was also depriving lower level players of sales they needed to get ahead. Jagex was doing the Right Thing. But the economy was affected by the sudden absence of Very Cheap raw materials, and prices rose due to demand.
A friend of mine returned to the game after a three month absence and experienced this painful reality. His 1k of cooked sharks (accumulated getting his cooking cape, ironically) were now worth only half their old value.
The nail on skilling's coffin was the GE (although most people erroneously assume it was the start of the problem). Formerly, rich skillers who disliked standing around Falador Park shouting "Selling weapon poison!" just kept their unalchable skill products (such as potions) in their banks. They had enough money that they didn't need to recover cash from these items. The GE ended that. Players dumped huge backlogs of finished products into the GE. Profits didn't really matter to them, because the stuff was just sitting in their bank anyway.
Unfortunately, it mattered to the rest of us. Years ago, level 60 weapon poison was sold for "big money". I couldn't wait to get there. By the time I did, it was worthless because higher poisons had been released. I struggled onward to reach level 81 herblore, painfully gathering herbs on my own (I hate combat), hoping to "get rich" from selling Saradomin Brews ... and by that time the toadflax and crushed nests were worth more than the potion. I don't bother to train herblore anymore - it's just a waste of money. So what if a new potion comes out? In no time it will be selling for less than the ingredients.
What concerns me the most is how this is affecting newer players. They can make money through the dreary, boring task of collecting seconds for rich higher level players, or through combat. There is ZERO incentive for them to train skills, because there is no profit whatsoever. And people with 99 capes have the nerve to wonder why skilling is going out of style?!