99% of what some people do is derivative. But if what they're doing is software, that's expressive duplication, and it's worth trying to DRY it up.
I think we have different intuitions here because it sounds like you're more in a service business than specifically writing software. I agree that a lot of any service business is standardizable, because it's mainly about people and their needs; that has a lot of regularity.
But I don't think the software creation part of a service business is standardizable over the long term. During the first wave of "put smallish businesses on the internet" each web site was custom, hand-rolled software. Early on those schedules were unpredictable, but for a while, it became a known, predictable business.
That business has, in the long term, been basically destroyed. People spotted the regularities and developed common code and tools. What was mainly a problem of software development became a (much smaller) problem of installation and configuration. The competitive advantage for those people now lies not in coding ability, but in customer service and in helping people manage the essential complexity of the domain.