What Shortcuts does undeniably have is youth, looks, and an established following; and never underestimate the value of those. AppleScript may be built on a better technical foundation, but that don’t mean squat if it can’t bums on seats. And the bottom fell out the AppleScript market a decade ago.
However, being an outside product is absolutely no disadvantage. I’ll rate a passionate team of third-party devs with a vision over in-house chair-warmers going through vague motions with zero direction or objective. Being within Apple can be a huge advantage in that it offers prime positioning within the OS itself; but that’s of no use if you’ve got no clue how to deliver a desirable product and sell it to customers in the first place (<cough>Soghoian</cough>).
Whatever the strengths and weaknesses of their product, the Shortcuts team cut their teeth and proved themselves out in the real world. I don’t doubt Apple bought WorkflowHQ as much to get those people as their product. As change of blood goes that was badly overdue.