But, in my admittedly simple application PMTiles can cover a lot of my visualization use cases with a thin Django app doing GEOJson for interactive layers.
So far you can draw shapes and unofficially add geojsons to the map. I am very excited adding the ability to link custom PMTiles in the future!
[1]: https://maplibre.org/maplibre-gl-js/docs/examples/pmtiles/
This solution was common 10 years ago but has largely been replaced by the alternative of vector tiles, in which data is sent to the browser and rendered there. That tends to give better performance and allow more interactive visualisations.
Hard to say for sure whether that kind of solution would have worked for them here, but it's quite odd to see such old technology written up as if it was the latest thing.
raster tiles have a specific size, but can't easily be tendered on demand.
vector tiles can be infinitely precise but can end up transferring way more data.
of course, whenever there's clear tradeoffs between techs, the modern gurus will vacilate between them, as the average programmer doesn't do the discriminate evaluation to pick the best tech, but what's popular.
"way more" - not likely, if it's an apples to apples comparison. Obviously there are extreme cases where tons of data is being shipped to the frontend that is not being used for anything.
The big advantage of vector tiles in practice is not needing any kind of tile rendering server in the background. You just generate your vector tiles (quick) then serve them straight up (easy). Simpler architecture and lower costs.