Most of the ones (for cnc and sheet metal at least) I’ve used do an estimate while you poke around and select options and then you send it for a final validation and quote.
If you're deliberately creating additional inconvenience to potential customers to handle your own resource/scaling issues... that's a 'you problem', and you need to figure out a better way to run things, or customers will just run to competitors who've already done so.
Right and they already said they have a massive backlog and are trying to increase by 500%.
Yeah mostly we just haven't got around to it as the burning fire is always increasing capacity vs demand. Defo agree we should not require login though!