When Salesforce launched, their product had two built-in tabs: "accounts" and "contacts". But very early in their journey, they decided to offer a way for folks to type in tab names that directly corresponded to their line of work. Car services could track "drivers" & "vehicles" and nonprofits could follow "causes" & "donors". Even though they had opinionated default tabs, they provided every user with a customized experience. "Flexible yet opinionated" at its finest!
Intercom had a similar approach. They're opinionated by default, but flexible under the hood. Even though they have a limited number of opinionated objects (basically conversations and customers), they also introduced custom objects so their users can model their data in a way that makes sense for their business.
Folks often try to put software in either the "flexibility" bucket or the "opinionated" one as if it was a one-dimensional axis. But it's not. The best products out there are both flexible and opinionated.