This is a common analogy but it never sits well with me. Really, the permissive licenses allow the code to show up in places that copyleft licenses would not allow it. There are a ton of open source projects used in Microsoft Windows or iOS thanks to their permissive licensing -- and neither Microsoft nor Apple are legally obliged to give anything back.
Copyleft licenses prevent the software from being forked into a proprietary program and the changes hidden from the user. To take a random example, if Microsoft took GNU gzip and included it with Windows, and then extended it with new features, Microsoft would be obliged to provide the source code to those changes. If they took OpenBSD's implementation instead, they wouldn't be obliged in the same way (though they still _could_).
Remaining entirely in the open source world, these licenses concern redistribution of software. A user on OpenBSD does not feel they have any less freedom than a user on GNU/Linux. They don't have any less freedom, after all. Users on both systems retain the full gamut of freedom. To run for any purpose, to study the source code, to modify the source code, to redistribute the software verbatim or modified. The difference shows up when it comes to this: Do you want to be an asshole? OpenBSD permits the option -- you can distribute a fork without the source code. You cannot do that with a GPL-licensed system.
The FSF and other GPL advocates usually ride on the premise that opening up the possibility for downstreams to be assholes is bad, with few exceptions. I do respect their opinions, but I feel like the history of open source (and the *BSDs, even) show that such assholes don't get very far. They simply cannot compete with the pace of open and transparent development and die off on their own. Frankly, being an asshole is an irrational and unprofitable (socially and commercially) move, and trying to nanny the behavior away isn't all that necessary.