At a high level a lot of systems are made of some kind of objects or actors. Things that transmit and receive signals or messages. Telecoms, the internet, Unix processes, micro services, smoke signals, human conversation and instruction. So maybe you can do pure functional down below but at a high level your system will always have some kind of objects (for want of a better word). Plus at a high level these systems don't share state. They can only do so via signals. This turns out to be a good enough solution for concurrency. People can demonstrate how you can still get deadlocks etc but if the granularity is large enough this rarely turns out to be a problem in practice.
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At a high level a lot of systems are made of some kind of objects or actors. Things that transmit and receive signals or messages. Telecoms, the internet, Unix processes, micro services, smoke signals, human conversation and instruction. So maybe you can do pure functional down below but at a high level your system will always have some kind of objects (for want of a better word). Plus at a high level these systems don't share state. They can only do so via signals. This turns out to be a good enough solution for concurrency. People can demonstrate how you can still get deadlocks etc but if the granularity is large enough this rarely turns out to be a problem in practice.