@Lorent Ha ha interesting theory, but in this case I don’t believe it’s intentional.
You’ll notice that if you enable localization, your IP addresses change. The reason for that I think is that Weblow has likely implemented localization as a layer on top of your site that is independent of the core site data. It looks as though they might be using a reverse proxy to handle the language switching and possibly the routing- much like Weglot, Linguana, etc. can do.
But, it’s just a theory. It would be good for someone who needs to change the primary locale to contact support and get a official answer. It may be that they can switch it internally, or that they have locale-migration tools that I’m not aware of.