Your random SaaS company is often a big shitshow. I've had more than one vendor Sales Engineer show me live customer data in response to performance or other questions. Startups and smaller SaaS companies in particular often demonstrate amazing levels of cluelessness.
For this client the only AWS product we were cleared to use was Lambda, and only for integrating Alexis into the product.
Zoom is the success story of these corona-times of ours; the headline alone is marketing gold, particularly considering nobody else in the "startupsphere" will ever give Oracle this sort of visibility - or even the time of day. At a time when Oracle is trying to push an image of being startup-friendly, this is better than the alternatives (each word they tweet on "helping startups" unleashes waves of mean and snarky jokes).
Netflix had a 5-day outage caused by issues with their private DC back in the day.
IT mgmt. decided their expertise wasn't in operating DC's, SV real estate was too expensive, and doing multi-region themselves was too expensive.
AWS was picked as it was the only viable cloud offering at the time, and the decision was made to be mono-cloud until later. (Azure was used for storing backups.)
Note that AWS was never used for large-scale streaming. Either a partner CDN was used, or now their own CDN.
Source: worked at Netflix.
The well-known US CDNs were used for streaming.
Also, the cloud they picked doesn't matter because:
1) They used their own ASG UI, Asgard, since AWS initially didn't have one.
2) With around 1,000 engineers, they could migrate clouds at any time at a future date (or build their own CDN. There was no silo politics as in most other companies.)
Amazon already has Chime.
However, as a customer dependent on that particular vendor, one wants to make sure that their cloud provider has no perverse incentive to deprioritize issues one encounters.
Smart move, really. Build a relationship. Better than funding the competition.