Two things, both limits of a browser tab. Your projects become real files, with native Open and Save As, a document you can double-click and a recent-files list, so a design can live in git or Dropbox instead of in one browser's storage.
And datasheets fetch themselves. Manufacturers serve most datasheet PDFs without the header a browser requires, so a web page is refused them; we saw that for five parts out of five. A model built without the datasheet falls back on the AI's general knowledge, which can be badly wrong. The installed app fetches from your own address and gets them.
We tried a server-side proxy for the browser and measured it against 150 real datasheet URLs. Half failed, all for reasons that come from one address fetching for everybody: hotlink refusals, rate limits, bot timeouts. In the browser the app still tries, since the occasional vendor allows it, and otherwise asks you to attach the PDF yourself.