The statement is to the market and to potential hires that they have runway. Showing how much money you've raised gives prospects (customer or employee) confidence that you will be around for a reasonable amount of time if they make bet on your business. Plus, it's social selling. Investors do due diligence. I can trust that this business has good fundamentals if VC X invested in them (in theory). I don't want to invest my budget, infrastructure or - heaven forbid - my time on this planet, on a place that's going to disappear.
Lots of startups solve meaningful and interesting things, but that doesn't matter if they can't show they have enough money in the bank to keep operations running.