The Natural Philosopher wrote:

the claims that 'Vlan segeregates traffic' are in fact silly, because
a normal; s3witch does that too.

But the level of segregation is different ...

All switches *try* to avoid forwarding packets to ports where they're
not needed, a VLAN switch *prevents* packets reaching ports other than
those they're configured to reach.

But switches DO provide security. Maybe you haven't used a packet
sniffer on a coaxial ethernet network, but I have, You can read every
packet between every machine passively. YoOu can do that with a wifi
password as well . That simply cant be done with a switch unless you
have a backdoor into the switch.

MAC flooding, ARP spoofing.