i strongly dislike planetscale and even i think this is not a useful or fair comparison .. sqlite works with local files, much simpler, no network latency, no HA
To be fair, if you accomplish the same effect without needing distributed computing, then the solution gets much simpler, you cut out worrying about network latency and HA*
* the probability of node failure grows very rapidly with the number of nodes. Same reason you probably don't need RAID for 1 disk, but you definitely do for a dozen
If you actually crunch the numbers, you'll see that the likelihood of multiple node simultaneous failure of a larger cluster is actually often as high, or higher than the likelihood of a single node failure on a non-distributed application.
Despite running redundant distributed set-ups, services today really don't have particularly spectacular availability. Google, Facebook, Twitter, Github; all go down or brown out frequently.