Limited is a great format that I'm glad you mentioned. Anything involving a draft is going to be pretty creative.
Just to be clear, I'm not saying that MTG is inferior to chess. I like both games equally well.
Beyond the decks/openings analogy though, I'm not sure Magic and chess really compare well.
I think the most interesting distinction is in innovators vs. honers; Gerry Thompson is now out of the game at the professional level, but he was one of the greatest honers who ever played the game. Gerry was not known for coming up with new deck ideas, and in fact the few times he tried it he did horribly. But his ability to analyze the tournament landscape week to week, and make the perfect couple of tweaks to existing deck shells, was unmatched.
So, I spend my weekends putting on a black uniform and working as a tournament judge at professional-level Magic events. And... maybe you're right that someone could do well at a local FNM this way. But at any sort of serious competitive level (even at the Pro Tour Qualifier level), your assertion just doesn't hold up.
You can see this in tournament results, by the way. Card availability is basically only an issue for casual/FNM play. At any sort of real competitive tournament, the field is made up of players who have access to the cards they want, and the winner is determined by a combination of preparation and skill.
Most importantly, you can see this in results from Limited formats (where players build decks using cards opened on-site from standard booster packs, which are unpredictable enough to constitute a random per-player card pool). Though there are certainly "Limited specialist" players, for the most part you will see similar lists of names among the top finishers in both Limited and Constructed formats, which drives home the point in a frankly undeniable way.