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Pedantic Grognard
Look, sure, back in 1853, when a Philadelphia publisher translated Uncle Tom's Cabin into German, it didn't violate Harriet Beecher Stowe's copyright, because all translation is paraphrase, and paraphrase is automatically not a "word for word" copy. The legislative reaction to that sort of thing happening was the creation of the category of "derivative works", and it accordingly has been more than a century since you could avoid copyright claims by avoiding making a "word for word" copy.The dragon stat blocks are copyright, you can't copy it word for word.
Yes, lawyers still use the cliche "copyright protects expression, not ideas". The problem for laymen is that "expression" does not mean just the literal words or images or sounds or whatever else is used by the medium. It can mean a particular concatenation of ideas.
A blue-scaled dragon that breathes lightning, on its own, is not likely to itself be enough to count as an infringement, no. That might have been in D&D first, but it's a fairly generic idea. Put it in grouping of specifically black, blue, green, red, and white dragons with acid, lightning, poison, fire, and cold breaths, the group evil, matched against a grouping of good dragons of brass, bronze, copper, gold, and silver colors, and you're going to have a judge rolling his eyes at you if you try a simple "I rewrote it in my own words!" defense.
So, sure, if you want to make something that was mechanically similar to/compatible with D&D but had mostly-different creative elements, then you didn't need the OGL. But that wasn't unknown in 2000; things like Tunnels & Trolls, the Palladium Fantasy RPG, and Role Aids* had thoroughly proved that for decades. What the release of the SRD under the OGL did was take a massive amount of D&D-specific creative work (mostly in the spells, monsters, and magic items), and made that available for use.
*Role Aids' first legal entanglement was a trademark suit from TSR, not a copyright claim. That suit was settled with a specific agreement on how Mayfair would use the AD&D mark to indicate compatibility. Its second legal entanglement was also not copyright, but because Mayfair, as it admitted in court, violated the settlement agreement from the first case. Even then, the court was pretty obviously looking to only impose something like a de minimis judgment against Mayfair, and what actually killed Role Aids as an independent line was TSR buying the line from Mayfair.