Yes, they shouldn't be dependent on Alphabet, they should back up their content and diversify platforms, but because we decided to allow monopolization of monetization of the web, and to vigorously encourage the surveillance based adtech of Google and Facebook, they control the full stack and effectively hold audiences hostage; you have to play on their platforms in order to engage with the audience you build, and a vast majority of the consumers of content are ignorant of the roles platforms play. If you leave the platform, you lose the access; if you have multiple channels, you get shadowbans and other soft-penalties to discourage people from being disloyal to Google.
We should have a massive diversity of federated, decentralized platforms, with compatible protocols and tools. People should have to think about CDNs and platforms as little as they think about what particular ISP is carrying their traffic between a server and their home.
There should be a digital bill of rights that curtails the power of platforms in controlling access, reach, and forces interoperability, and eliminates arbitrary algorithmic enforcement, and allow due process with mandatory backout periods giving people the reasonable opportunity to recover digital assets, communicate with audience, and migrate to a new platform.
The status quo is entirely untenable; these companies should not have the power to so casually and arbitrarily destroy people's livelihoods.