Certainly they can't be built strong enough *that way*. Look at it: a few bolts down the middle of a very narrow base. These fin keels are much more like an airplane wing than a traditional keel shoe. Imagine taking an airplane wing, passing a few bolts through the middle of the root rib into the fuselage skin. This is the construction method on these boats. It is ridiculous. And yet airplane wings don't have struts or wires anymore and they don't fall off - even with very large spans. They do it by passing a structural spar into the fuselage to carry the bending load. The bending moment can be resisted over several feet rather than a few inches, cutting stresses to a small fraction of their ignorant method.

For example my ASH26E: