The poster i was responding to equated subnetting to vlans. I might have misunderstood what they meant though. It sounded like they wanted to use the same subnet per vlan, which wont work if you want them routed in the same gateway.
Reading it again they make it sound like you can't subnet all of these networks on a switch without vlan, which you definitely can. I could for example connect 4 different devices on the subnet 192 168.10.x/24 and have them reach each other. I could also connect 4 more devices in the same switch but on a different network 192.168.20.x/24 and it would work.
Sorry about my confused rambling 😅 Yes, the example was to demonstrate the difference between subnetting and vlan. Albeit simplified. What you said is right.