You know what? They're technically correct. There's historically plenty of computer systems which came in multiple different cases, sometimes that's still the case but the most obvious examples are historical, where you would get something like the CPU (yes) in one case and then a huge-ass card reader in another case and drum memory in yet another. Those drums were used as RAM. Each case was standing on the floor, at least chest-high.

Simply integrating various peripherals into the CPU doesn't make the CPU any less of the CPU. Even ignoring the case thing and just looking at the CPU package (or even die): Modern CPUs contain a lot of things that would've been external to it, or even in a different case, in the past. You'll hear the term "SoC", system on a chip, thrown around but that's misleading most CPUs nowadays are SoCs: You have your CPU cores, yes, but you also have a memory controller, you have storage interfaces and general IO (PCIe is a storage interface), as well as a GPU. It's been a long time since mainboards came with northbridges. Newer CPUs may have enough memory on package to reasonably run without external memory (and not just "use the cache as ram during early boot" kind of stuff).