Upgrade or alternative upgrade?

So, it turns out that this type of build is only possible on maps where it's possible to start a town with a tavern already built from the beginning?
Then, such a start, supposedly allowing for a quick transition to dragons, becomes irrelevant and merely a privilege for a specific set of maps. Okay, I understand. Thank you for the explanation. I've read about this development not only on this forum but also on AG, and it's quite popular there, so I thought it was possible on all maps.