There really are no other [sane] alternatives ... unless you want to go to 50 vendors to save 50 cents per user per year on licensing (and waste 50 hours a month of everyone's time trying to get them use tools that don't integrate in any understandable/low-friction manner)
this is not about saving money, but about avoiding the behemoths that dominate the market. it would be rather disappointing if the options were so limited.
Wasting 10s or 100s or 1000s of 1000s of hours of time across an organization is stupid just for the sake of "avoiding the behemoths that dominate the market"
i prefer 50 because the likelihood of them failing or denying service all at once is lower. much lower. this goes beyond email, but it would be insane to put put everything my business depends on into the hands of a single company.
Your choice of 50 unrelated, unintegrated vendors introduces 50 single points of failure to business
That's incredibly stupid - unless you truly have no choice
It introduces a huge amount of unnecessary risk to the company, and immense overhead in additional personnel (product admins, contract management, vulnerability monitoring, end user time/training, etc)
It's why multicloud is mostly not a thing: outside of a few niche cases, running cloud workloads across multiple providers is more expensive than running it all in one. Sure GCP might have something that's cheaper than AWS, and AWS than Azure, and Azure than GCP - but now you have to manage data going into and out of three providers instead of one, three separate contracts, three sets of credential groups, etc
