If I’m understanding correctly, this is saying that isolation between different clients on the same VLAN is broken? But this attack doesn’t break isolation between VLANs?

So the major issue is if you’ve got a guest network on the same VLAN as your main network

We (uk scout group) use g suite or whatever they call it these days. The Google connection isn’t ideal, but we get it completely free, the t&cs and level of control over it are a lot better than consumer gmail/drive, the learning curve for techphobic users is about as shallow as possible, and we don’t have to spend volunteer time on maintaining the platform. So definitely worth it for us but your situation may vary.