We know that a stone giant is at least about 15ft tall, because otherwise it couldn’t control 15ft of space. It doesn’t have arms down to its feet, after all.
Would you also say that "We know that a kobold is at least about 5ft tall, because otherwise it couldn’t control 5ft of space. It doesn’t have arms down to its feet, after all"?
Space controlled is demonstrably an abstraction that does not care that kobolds are (per
Volo's Guide to Monsters) "between 2 and 3 feet tall". Therefore space controlled does not, in fact, tell you what the minimum height of a Huge creature is. If the next 5e monster book has a Huge giant that's given a height of 12 feet tall in its description, neither the size category nor the height given contradict anything already established in 5e in the slightest.
So, then, what ties this point into the thread? It indicates that even if giant heights had been entirely consistent from edition to edition, frozen at the numbers given in 1974, that doesn't indicate that "space controlled", reflected in square base sizes for a grid, would stay the same edition to edition.
We can demonstrate this, in fact, by comparing 3rd edition with 3.5. The giants didn't change either stated height or size category between 3e and 3.5, but the space they took up on a battelmap
did. A 3e hill, stone, frost, or fire giant had a "Face/Reach" of "5 ft. by 5 ft./10 ft.", meaning that it only took up one 5-foot-square on the grid. Which meant it could only be directly surrounded by 8 humans, and 8 fire giants could directly surround one human. Any fire giant miniature made with a base size compatible with 3e would be incompatible with the 3.5 rules, and any 3.5 mini incompatible with the 3e rules, even though the official size of a fire giant didn't change in the slightest.