I'm not so sure. No numbers to prove it, but I think an optimized crown-type fork can be both lighter and stronger than a unicrown.

When you make the blade heavy enough to be strong as the "crown", it's heavier than it needs to be all the rest of the way down. And they were mostly round tubing, which is suboptimal for forks, whose main loading is fore-and-aft, not side-to-side -- oval is better there. (Fork blades are oval for a very good reason.) Unicrowns eventually were made with oval tube, but then your "crown" is oval too, which is not optimal in that area, where forces switch from bending (down below) to twisting (torsion) in the crown area.

Both types can bend in a crash, but I don't like the way unicrowns bend, with the "crown" area collapsing, so that its strength rapidly diminishes. The bend in a crashed crown-type fork is generally more gradual and distributed. Only rarely do they kink or collapse, in fact I don't think I've ever seen one that did, other than from a disk brake on a too-thin blade. They bend in a correct way that optimizes the amount of energy absorbed, which can mean that YOU fly off the bike with less kinetic energy, some of your KE having been absorbed by the "crumple zone" in the blades.

Another point of difference is the ability to straighten a bent fork. Yes (sometimes) with crown-type, but no (almost never) with unicrown, due to the way the tube collapses in a smallish area when they bend. Straightening it will not remove the distortion in the collapsed area, it'll only put another opposite bend somewhere else, leaving the fork seriously weak.

Optimized crowns are hollow or basically as close to tubular as possible. Good examples include Nervex Pro (as used on PX-10 and a hundred others), and the faux-tubular Raleigh "thimble" crown. Even some crude-looking sand-cast crowns from the olden days were cast with a large hollow area inside, between the steerer and blades.

The crown on the fork in question (see the OP) is not hollow AFAIK but I never cut one open to see. I think it's solid and thus it is far from optimized. Definitely strong enough, just heavy from its inefficient shape. Two-plate crowns, and some faux two plates, are better than a solid chunk of steel, but still not as good as a hollow crown.

One more thing to say, I wish people would stop attributing the idea to Tom Ritchey. It was used in BMX and cruisers long before Tom ever made one. Tom doesn't claim to be the inventor (that I know of). He deserves credit for being the first to use it on relatively lightweight MTBs, just don't call him the inventor.