Of course AWS wants you to use them. They would never market for a competitor, that just makes 0 sense.
In terms of reliability, AWS and GCP have solid track records in terms of multi-region availability (I can't say the same about Azure... They seem to be years behind still.) Cost absolutely goes up when you're building out regional fault tolerance, but that's true whether you use a mixture of cloud providers or any specific provider. If you need high availability, you need to waste some level of resources (and in turn, money), it's part of the design.
I'd argue almost anyone would be fine running out of a single aws region. There are specific cases where extreme availability matters, but in that case you're making the tradeoff of cost and simplicity for reliability.
It would be interesting to see something like a study on whether using multiple regions in one cloud provider makes more sense over having your load spread across providers in terms of complexity versus fault tolerance.
In terms of reliability, AWS and GCP have solid track records in terms of multi-region availability (I can't say the same about Azure... They seem to be years behind still.) Cost absolutely goes up when you're building out regional fault tolerance, but that's true whether you use a mixture of cloud providers or any specific provider. If you need high availability, you need to waste some level of resources (and in turn, money), it's part of the design.
I'd argue almost anyone would be fine running out of a single aws region. There are specific cases where extreme availability matters, but in that case you're making the tradeoff of cost and simplicity for reliability.
It would be interesting to see something like a study on whether using multiple regions in one cloud provider makes more sense over having your load spread across providers in terms of complexity versus fault tolerance.