A few thought : 1/ parse wasn't a core service for facebook, nor a relevant source of a revenu AND their API wasn't standard. Those points combined made it very risky for people to use it. 2/ since they open sourced their API now, and the service was a paid service, there's a very high probability that someone will very soon create a 100% compatible PAAS. 3/ firebase will be next to shutdown. Not because they suck, b…
Google maybe.
Microsoft never - if it's one thing that is in their DNA than it's they always have undocumented API edge cases, so they can change them right in front of a competitor - they have a very long history doing that. Ask Apple (Word, IE, etc), DOS-competitors (DR-DOS, etc), IBM (OS/2, DOS, OpenOffice, Lotus, etc), "open" Office format (docx, xlsx, pptx = weird XML serialization of their old binary OLE2 based Office format), Win16API, Win32API, NTkernel API, and many more.
You are right with AWS.