Oh, the integrated players (now pretty much just Intel and Samsung, but in the past people like AMD as well) have other things they make on these older fabs- modems, OOB managers, USB controllers, all the other chips that go on a motherboard, but these are lower margin than a pure-play fab can get selling to all of those customers who don't need the latest node.

This is one reason Intel and Samsung are both hesitant about going to the next node- Intel has put out official statements that they are only going to 14A if they can get Foundry up with a significant partner, and Samsung is hedging their bets and being cagey about their own 1.4nm node (at least in English, I haven't seen any direct demand for a major foundry customer from Samsung, just statements saying that they were going to be delaying and might not be building it at all).