It all comes down to what you trust each type of device to do and how you want to handle their traffic.
I have seven VLANs, with each one’s traffic being treated very specifically. The subnets for each VLAN route to specific interfaces on a virtualised OPNsense firewall, which is where my traffic handling and policy enforcement takes place.
Also remember VLANs are just plain useful for segregating traffic, particularly broadcast traffic, without having to invest in separate switching/routing for each subnet. Having a single managed switch that limits the broadcast domains for you is a really efficient way to (physically) setup your network.