Lim Goon is done with maple.

There can be a difference. From most hobbies, there's always something left behind after you quit them. If your hobby is something that requires studying, you're left with the knowledge about it (this one applies to all of them actually), If it is related to phisical work, your body will always remember how to perform them to some extent and you can gain physical strengthening (or injuries), but in MS and videogames in general, the moment you quit, the moment all the time and everything you've spent goes to waste. There are exceptions of course, but unless Limgoon sells all his items/account for real money before quitting, this can be applied or not to him.

Discounting experiences gained is flawed logic. To use myself as an example, I give a substantial amount of credence to the time I've played this game in the various skills I've acquired through learning to be a better player. People who organize boss runs and manage guilds effectively are more common to have good time-management skills, for example. If you're skilled at making enormous amounts of money in game beyond scamming and hacking, you more than likely have a basic understanding of economics to an extent.

Another great benefit that most people don't acknowledge that I personally swear by is the community aspect. Sure, this doesn't apply to anyone, but spending so much time online chatting with others has in many ways influenced my ability to write effectively. There're plenty of folks who could care less, but whether we realize it or not, there are many academically-oriented skills that can be strengthened by playing a game like this.

Focusing simply on the fact that items and equipment attained are ephemeral is missing the point--there's far more to be gained from playing online games realistically than what is only tangible when in-game.