They did, but they also said it was a pretty hard slog. You really need to be well prepared if you're going anywhere near that sort of territory. Plenty of people have died out there because their cars broke down and/or they ran out of water, etc. Not a place to take chances.
I think it's important to realise the true scale of the distance we're talking about here. It's a total of 1,384 miles from Perth to Broome by road. Have you ever driven that distance before? You need guts, stamina, and intelligent preparation - to say the least.
I've driven from Perth to Adelaide (1,672 miles) and back again (a total of 3,354 miles). In fact, I've done it twice. It's a hell of a slog - but I am willing to bet that it's still easier than the Perth-Broome run.
I would advise you to fly up to Broome if you can afford it, or take a coach if your budget is tight. Arguably cheaper than hiring a car and driving. Certainly safer. And hey, in true backpacking fashion you could make some new friends on the way!