The real reason is the thing you highlighted: "I can see there are some NGINX Plus features that are free in Caddy." Sadly it seems that NGINX is now crippleware. Personally I find it risky to depend on open source organizations who refuse to accept important features to the project, so they can sell those features as proprietary.
Is this still the case?
And to be clear, only builds produced by the official Caddy website used to be commercially licensed (not anymore). But the code has always been open source, and you could always build from source for free for commercial use.
> But the code has always been open source, and you could always build from source for free for commercial use.
Back in the days there were some workaround projects that build for you. Well caddy was relatively new then so I abandoned it for my projects.