One key missing factor: live replication across three clouds is not just a technical problem, but a cost problem, because the egress costs will be murderous.
Not everyone rips you off on egress fees the way Amazon/MS/Google do. Quite a few of the 2nd tier providers (eg. Vultr, Linode, Digital Ocean, Upcloud, etc) offer $0.01/GB for public outbound bandwidth with a free allowance each month (usually anywhere from 1-10+TB/month/instance depending on what you deployed). Some companies even waive fees for companies they're partnered with (eg. if you use Wasabi or Backblaze B2 instead of S3 you won't be charged transfer fees to a number of cloud providers or Cloudflare thanks to the bandwidth alliance).
It's not mentioned in the blog, but we are actively working with other providers to bring them on board. Hopefully we will have Digital Ocean soon, and I am hoping for Packet after them