Did you know that, playing MMORPGs can make you smarter? Do you know what traits do they enhance in you? If you don't, then you came to the right place.
Forced to focus my attention in one thing at something so subjective as "intelligence", I will not go over the different branches that this article may lead me to. I'll just work with Howard Gardner's theory of Multiple Intelligences
Gardner's model proposes 8 areas of intelligence, you exercise all of them by playing MMORPGs.
How does this happen? To analyze this, we will use the "Jack the Ripper" method, taking it by parts.
Logical-Mathematical Intelligence
First, we should observe what happens with logic, math and strategy capacities. After all, they are considered of prime importance in our contemporary educative system.
As we play any MMORPG, the first thing we consider is optimizing our character, this is, how does the player uses algebraic and statistic methods to better hurt an opponent or heal an ally more efficiently (knowing "our own" stats to not hit by 999 someone that is at 1 HP or heal by 9999 someone that is only hurt by 10... Is what draws the line that divides "pr0s" from noobs; No overkill/overheal).

Recount, for WOW
You guessed it, that thing above is an addon that allows you to check your in-game performance, there's several options that allow you to see deeper data to "tidy up" your combo and make you a better player.
While Damagers focus on -duh!- Damage, healers have a harder time, controlling their party's HP, keeping event the newbiest noobs alive!
Strategically speaking, at least in any respectable MMORGP, the potential variations of a character build allows you to costumize it as you please, to better suit your style and needs. This, forces you to think ahead a lot of things. Where a noob plays like Leroy Jenkins, a good player sets up a group strategy and a plan, complementing skills and abilities.
PS: This was an advertisement campaign!
Algebra, statistics and logic, are exploited to the maximum, for a better gameplay experience.
Linguistic Intelligence
Of course, whenever there's people doing the same thing, there's communication. This one, generally speaking, is done over VOIP channels, like discord or teamspeak (among many, many others)
This communication is imperative at a point and efficiency in those messages is must.
Clear, brief and concise instructions are a must whenever one does not have much of a time window to perform a task, under the pressure of one's opponents!
Abbreviations, acronyms, unique terms are constantly used at several game platforms. This unique language was created over the last 30 years. New terms are forged everyday for specific games yet... Every MMORPG player knows what "HP", "mana" and "pots" are.
An outsider (like, a candy crush player) would feel like a fish in the desert if s/he ever wanted to join a conversation about an MMORPG.
You are FORCED to read in many games, you are FORCED to learn and understand text in a way not many schools today force children to. Text comprehension is taken to the limit at some "quests" that include riddles.

Bodily-kinesthetic intelligence
Hand-eye coordination play another key role on good players (If you didn't know that, I dare you to watch a Professional Korean Gamer working). This is not only talking about finger agility, but also prediction of the opponent's movements (players and MOBs, mobiles non-player opponents).
Hand-eye coordination in gamers is way above the average people. Some studies point out that the motor and perceptual-spatial skills are also enhanced in them, better reflexes and response time.
Intrapersonal Intelligence
There's people, you've to interact with them!
The ability to communicate with them was stated at a previous point. Intrapersonal relationships go in a deeper level.
It wouldn't be a surprise to find "guildies" becoming real life friends, partners. It is nothing new to hear of a game guild helping out a member in REAL LIFE problems that arise. Contrary to what many grandmothers believed as Online Gaming appeared, social skills are boosted at MMORPGs in the case they exist.
The ability to organize large groups of people, demagogic skills, politics: are all required for good guild leaders and officers on the "good" guilds".
You want to see the intrapersonal intelligence at its best? Go to any GameCon, and you'll see people that never saw or talked to each other behave as if they were best friends since they were 5 years old, If that is not Intrapersonal Intelligence I don't know what it is.

Visual and Motion Intelligence
Some MMORPGs worlds are HUGE. Continents, countries, territories, dungeons. You end up knowing them all by heart.
Mechanic transportation methods, portals, or even walking require quite a lot of "memory" in our heads to go from A to B as fast as possible.
At dungeons, knowing the safe zones and corners can be the difference between success and utterly failure. Knowing how to move around to prevent taking damage is also necessary.