You can have a very complex networking infrastructure with very simple proxies and network segmentation. What specific feature do you have in mind. Load balancing and resource synching?
Often there are proprietary solution to proprietary problems you would otherwise not have in the first place.
I used AWS for a long time but I am back to hosting myself. What arcane network requirement would that entail? I don't think there are benefits even for government scale problems.
Anything involving private links to other organisations, cloudflare or API management to multiple endpoints scattered over on prem and hosted. I would hope you could avoid most of the pitfalls by avoiding the proprietary solutions but sometimes there is no feature parity between host services and you might be stuck.
The private links in Azure are particularly specific.
Often there are proprietary solution to proprietary problems you would otherwise not have in the first place.
I used AWS for a long time but I am back to hosting myself. What arcane network requirement would that entail? I don't think there are benefits even for government scale problems.