I guess the word might've been used in a facetious way, so to speak, the way Mr. Cobb in Inception tells Ariadne (can also be seen in the trailer), "Well, it's not strictly speaking legal" when it's clearly illegal.

But I agree, the word is very misleading in the article's context.

the amount of times i get called bullshit for doing an en passant or uttering the word zugzwang...

Serious question: Does en passant happen often? I've never seen it happen in the wild (i.e. in games I play), but I just play casually with people.

It happens a lot more to people who don't know the rule.

I've definitely seen it, and I have never played a ton of chess.

More common in blitz. Carlsen executes it in the 2013 world blitz championships I believe, and I've had it done to me and I've done it as well in 1m/2s games.

Even if it doesn't actually happen, it often impacts play, especially in the end game.

It's relevant in almost every game, if you include variations that you have to consider when deciding your move.

Yeah, but putting "strictly" there does not change the meaning of the sentence, it's just a superfluous word.

"strictly" changes the meaning of the sentence. it suggests that there are "strict" and "not so strict" interpretations of the chess rules, and that if you're not so strict, the move is OK.

but promoting to the other color is not allowed, even under "not so strict" interpretations of the rules of chess.

an example of things that may be permitted in "not so strict" chess: taking back your move, not moving a piece even though you touched it, talking to the other player, agreeing to play on even though you've had a threefold repetition.

Allowing promotion to any piece sounds perfectly in line with "not so strict" chess rules to me.

If my opponent would use that move, I would probably consider it as a severe case of rule of cool. ( But this may be the reason, that I prefer RPGs to chess. )

I mean really, the rules are the rules, and there is no ambiguity. So a "strict reading of the rules" is the same thing as a "reading of the rules." Because, as you say, there is no such thing as a reading of the rules that violates the rules and is thus merely "less strict."

For example, under the rules, not moving a piece you touched and promoting to the other color are the same: illegal.

The examples you are giving are simply cases where the other player is likely to let you break the rules if it's a very casual game.

So again, having "strictly" in the sentence is, technically, purely redundant.

It's a dumb thing to say, but then again, it probably made the piece more suspenseful and thus more fun to read.

You seem to imply that all rules are equally as important as one another, while I would say they are not. For example, in a casual game of chess, most would be okay with some of the aforementioned deviations, like taking back a move. I do not think most would accept it if you started moving your pawns around like queens.

Either English is not your first language, or you have never played a game with a child!

It gives the sentence a nuance that suggests ambiguity, as if prohibition of this move requires some particularly "strict" reading of the rules. I agree that makes the sentence weaker, and given the gravity of the sentence, makes the article seem somewhat amateur.