I think the example at hand proved that buying up supply and then selling at a higher price at least short term didn't work, based on at least my empirical observations of new burns being listed for 1500 gold 2 hours after this post. Now, long term speculative buying is probably a thing, but that's not really market manipulation. Unless you think that longing DJI is market manipulation.

Buying up cards and bundling them via a 3rd party site is not really market manipulation. Unless you also think that selling me a meal at a restaurant for more than the cost of ingredients is also somehow market manipulation.

Advanced knowledge of deck ideas on hextcg.com could be market manipulation if it was in fact advanced (and not just exploiting public information the fastest). But to be honest, if the external writers who create content every two weeks want to speculate on some cards that they plan to feature in a deck, that's a pretty cheap price to pay for that content.

Cards going up in value after being featured at a large tournament. Well, that's intended and one of the primary reasons why we have tournaments with large prizes. If you think that's market manipulation, I bet you really hate the fact that pro athletes wear brand names when they enter the court/pitch/field/rink/whatever.

As far as Laissez Faire vs. free market: sure by the strictest definition, you can say that Laissez Faire is a doctrine of complete non-intervention. But to tell me that Hex is a free market, but doesn't fit your definition of Laissez Faire is pedantic at best. And while we're being pedantic: you could argue that the economy, which encompasses and facilitates non-AH exchange of goods (i.e. mail and CoD), is in fact not limited by a tax and does not have price floors.