Pretty much the whole book is my fault, but it wasn't created in a vacuum.
The information on WBH p. 195 is taken from that of High Guard (p. 69) about the minimum requirements to qualify as a class of starport.
Well there are formulas on actual docking capacity - at both Highport and Downports (WBH p. 198), shipyard build capacity (WBH p. 199), and annual Shipyard output (WBH, p.199).
Then it would be a hangar, with perhaps connections for fittings no longer functioning or usable, or just a perfectly good shipyard without enough workers being used as a hangar, a storage compartment, or a tactical training zone complete with randomly placed shipping containers and miscellaneous junk.
The formulas have DMs and a 1D roll for variance, and like everything else in the book can be totally ignored or handwaved into something else, but it provides a baseline number to consider. And as
@ottarrus says, in most cases it is ""Traveller Gearhead Stats Up Unnecessary Stuff, Part 12" or maybe Part 13... anyway, if you're doing a sector or trying to look at a Pocket Empire's capacity to do Pocket Empire Things, then it has value. If you're just trying to figure out if the port can fix your fuel pump, it's entirely unnecessary.