Quote Originally Posted by Mastikator View Post
If the party wants to visit a plane, but doesn't have access to planeshift, then the DM is not *obliged to give them other means.
If the party wants to visit a plane, has access to planeshift but not the right tuning fork, they may **ask to craft or buy one, it's a much smaller ask from the DM than to put a whole archmage or portal.
One of the baseline assumptions of the game is that other planes of existence exist and that there are ways to travel between them, with many of those methods already outlined in the PHB and DMG.

So, sure the DM doesn't have to literally hand the players a Planar Travel Device, but it should be possible to find a way to travel to another plane even if none of the PCs knows Planeshift. How hard or easy it's going to be is a DM call, but there are other methods for planar travel (including "find an NPC mage who can cast it for you" as the simplest one).

If the DM wants to "ban" those options, it's fine, but I expect them to communicate it as part of the pitch. I once made a setting where travel to the Upper and Lower planes was barred, and this was explicitly stated.

The worldbuilding implications of "there are mages capable of casting Planeshift", "there are planar portals" and "it's possible to buy or craft a tuning fork for Planeshift" are all pretty much the same: planar travel is possible.