Because in both scenarios they are effectively queries.
ADPs (as they do not initiate the Jet/ACE database engine at all) can not include linked tables in anything like the traditional sense. Linked tables are, by definition, Jet wrapped to support local functionality.
In an ADP the offerings provided by "Linked Tables" are SQL Server equivalents.
Whether you select "Linked Server" or "Transact SQL" the resulting means of accessing that data is via a simple View created to access all records from that external source. The only difference is that if you choose "Linked Server" then a Linked Server is created on your server which the View accesses with a query such as SELECT * FROM [LinkedServerName]...[tblName]
To me, this is overkill. You're impacting upon the server (by creating a persisted object) to support something you're wanting to create (emulate) in a client application.
The "Transact SQL" option means you'll acquire similar functionality directly in the query using the OPENDATASOURCE function. No persisted linked server.
Either way - you're only emulating that which MDBs/ACCDBs offer. Linked tables there are a fairly unique concept with great versatility. Yes there are downsides (especially for the unwary) but they offer continued use which is simplicity itself.
Cheers.
