It "means nothing" that the way that government systems get set up for government data is all using Microsoft tooling?
"Better" isn't relevant, which is my entire point. The reason people choose Microsoft isn't "it's better for this", it's because every consultancy out there, every government agency or affiliate, etc, is going to push Microsoft very very hard.
FedRAMP is demonstration that the solution met some assessment of controls in alignment with NIST 800-53. As a checkbox, it’s almost as dumb as FIPS 140, and like FIPS, you need to asses risk for your implementation regardless of these things.
Microsoft wins deals because their product catalog is well engineered to incentivize bundled subscriptions that drive marginal adoption. The user facing products are better, Entra is generally right there, and that’s a pivot into many other scenarios that drive spend.