Sure, as in the past, I agree, and have myself previously advocated for that. But as previously noted, until you have reached out to each and every client out there, and convinced them to change their ways, server operators in certain countries (and I am explicitly not using the term “zone”) are confronted with the challenge of being assigned too many clients, and need to deal with that. In a dream world, we wouldn’t have the issue. In reality, we do, and as it looks, for some time still.
Also, use of the “local” zones are not the only issue, the current GeoDNS approach is. Even if you use the global zone, if the GeoDNS server gets an idea as to the country you are in, you’ll again end up limited to the servers of your country zone, even if you have configured the global zone, not a local one. See the sources mentioned here, and then try it yourself.