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One could remove the ATM overhead, but then one has a point-to-point link, rather than a link over which data from many sources can be multiplexed.

Rather, that leaves us with the excellent (very desirable) option of a link where data from many sources are multiplexed by TCP/IP....

I do not see what ATM buys in this situation.

Like any technology, ATM will not be all things to all people. If all you are looking for is a "big, fat pipe" below IP, you will look at all your available options in addition to ATM. (You will be looking at all options regardless). In the end, you will choose whatever makes sense technologically AND ECONOMICALLY. Shikhar