Why Landing zone sugguest only 1 VCN at hub network?

Summary:

Hub/Spoke network structure principle

Content (please ensure you mask any confidential information):

Hi guy,

Our team is working with customer in the architecture design phase. The customer has proposed splitting the network Hub into multiple VCNs (in/out/inspect). However, most OCI Landing Zone references use a single Service Hub VCN. We’re investigating the rationale behind the single-VCN approach so we can explain it clearly to the customer. Could you please support us with guidance and supporting points