The 2019 Ranger (US) isn't available yet, it's quite a bit different than the older models. According to the Ford Web site the prelim specs (for 4x4 model) are 1650 payload and 7500 towing. Vehicle weight is 4354.
I agree you'd be foolish to tow 7500 or even 5000 lbs frequently with it. But I'd like to be able to occasionally tow 5k and for short distances. Going by MSRP an F150 would be at least $5k more, probably more like $7k. You get more truck, sure, but it won't really fit in my garage and it's a pain to park anywhere.
Is it right for everyone? Of course not, but it hits the sweet spot for me.