> they could

They could, but they didn't and instead they wrote that blog post which, even being generous is still kinda hard to avoid describing as misleading.

I would not have written the post I did if they had presented a multi-node bare-metal cluster or whatever more realistic config.

They could but then that exchanges cost savings for complexity. You now need to keep them in sync and it is double the cost.

I agree with the other poster, this is fine for a toy site or sites but low quality manual DR isn't good for production.