To be fair, that's fairly anecdotal. They're not inherently more unreliable than most cars, and at the very least they're fairly cheap to fix when they do go wrong.
There's an abuse factor in there too. Many people buy Fords and a great number of those people probably don't treat them great. Mechanically my old Mk4 Fiesta was perfect because an old gent owned it for the first 15k miles and I looked after it for the next 6.5 years. It just started getting a bit rusty in places. Which is still the main enemy of old Fords.
But most are driven into the ground, badly serviced (if at all), thrashed by sales reps or crashed by teenagers. It's why I partly feel sorry for the 2nd-gen Renault Clio's reputation for unreliability, since 99% of 2nd-gen Renault Clios are owned by new drivers who roar around like total bell-ends the whole time. They're not so much unreliable as less capable of withstanding unrelenting abuse from idiots than some other cars.
No car is truly immune to bad driving - witness how many Golf Mk4s are on their last legs these days now that they can be had for less than a grand and any old berk can afford one.