I think he was being figurative in his expression.
Either way, while it definitely helps to have firsthand experience with the character you're discussing, you don't have to "main" the character to provide productive insights. I don't think
@TriTails plays Pit in any meaningful capacity, yet he perfectly described Pit's off-stage game, even more concisely than I'd have done. Sometimes you can get equally good insights by fighting the character rather than playing them directly. It definitely offers a different perspective than you might be used to just from controlling the character yourself.
It's a fine line between just discussing your own character and talking about something you know nothing about. Neither extreme is very helpful. On the one hand, you can have discussions based on one-dimensional experience with a certain character and nothing else; on the other hand, the discussion can be misinformed theorycraft that has no basis in reality. You have to have
some cogent knowledge of the character to engage in a proper, productive conversation, you can't just make up statistics out of thin air with no prior experience and maintain it's
de facto truth; yet short of "maining" every character in the roster, you can't expect knowledge to be disseminated based on the criteria that, if you don't play the character, you don't know the character.
This is relevant to Meta Knight for one simple reason, and that reason is the fact that
Meta Knight is a very easily misunderstood character. This is a character that was initially considered unviable trash due to weird hitbox placement and no reliable combo game, yet who became a tournament-viable threat over the course of a couple of balance patches. To the casual observer, this seems to have happened overnight: until the likes of (initially) Leo and (currently) Abadango began taking games off of big-name players at relevant tourneys, most people with a passing interest in the tournament scene wrote off Meta Knight as a flash in the pan and nothing more. Now that Meta Knight has become something of a vogue trend in recent times, with people frequently citing him as a potential candidate for top tier and vague whisperings that he might have an even matchup with Sheik (disclaimer: I am not saying he does or does not), you have people suddenly taking an interest in what he can do and chattering about why he's suddenly become a relevant character in the meta. This will naturally begin a process of people trying to hop on the bandwagon and yield the same success that these top Meta Knight players have, near-invariably with no success; this then has the contingent side-effect of convincing a vocal minority that Meta Knight is just (to purloin the popular parlance) a "fraud" and that top players just rely on cheese and easy-bake combos to succeed. This is both unfortunately misinformed and potentially detrimental to greater understanding of the Meta Knight...meta. Then you have the inevitable few pessimists who still have a sour taste in their mouths from
Brawl and think Meta Knight players want to exploit Smash 4 in the same way, just ride the galactic crusdader's midnight coattails to an easy victory.
The truth, as I understand it, is that this is not the case and people have greatly misinterpreted the character's inherent ease of use.
Amadeus9
pointed it out a few minutes back: Abadango didn't just pick up Meta Knight one day and decide he was going to win tourneys with him, he practiced very hard behind the scenes and is still trying to perfect Meta Knight's holy grail combo. I understand that this is something that even other experienced Meta Knight players have difficulty with, and it is something that requires dedication and training to become absolutely adept with. Then there's the fact that people have conflicting opinions on Meta Knight's own abilities (i.e. is his neutral good or bad? Is the holy grail combo a cheap exploit or a brilliant revelation?), exacerbated by the fact that there is still just a handful of very good Meta Knight players out there representing the character and demonstrating to the public what he can do. It might be something to do with the fact that development of the Meta meta happens to be mostly done behind the scenes and discussed between Meta Knight players themselves, which, in our days of spectator viewing and results-driven frenzy, means that for most people it does not exist and Abadango et al have just used some kind of distinguished demon magic to kill people off the top at 40%. Meta Knight players know what they're talking about, because they study the Meta meta day in, day out and have dedicated themselves to pushing forward with new discoveries and exciting tech - something you can't just pick up and play and expect to do well with. In that sense, I can understand why Meta Knight players can get frustrated with non-Meta Knight players trying to vindicate their understanding of the character despite having no firsthand experience, since the efforts of the Meta Knight players is a constant project based on deep technical understanding, a desire for innovation and an abiding interest in playing the character. In a nutshell: the Meta Knight meta is serious business, and woe betide ye who disrespect the understanding these guys have of the character and the effort it takes to do what they do.
Of course, everything I've just said has been written from the perspective of a non-Meta Knight player, so I might be totally off in my definition. I'd be interested in hearing what others have to say in response, since I know I am quite guilty of shifting the topic of conversation to my own main whenever I get the opportunity to do just that.