A new business hasn't proven itself viable therefore it's a huge risk to a bank.

Between personally guaranteeing a loan and not having the funding available at all, I'd take the former.

Once the business has been trading for a while and shows it has a working model, it shouldn't have any problem financing without a personal guarantee.

Either way, limited liability remains crucial. You're still in control of how much personal risk you're accepting, putting a backstop on any loss.