You need to have AWD for the Maverick to have the 4000 lbs rating. It's going to be sending power to the rear wheels when you're towing.

You can't really compare the tow ratings with a 1985 Ranger. Back then the ratings were not standardized and were generally inflated for marketing purposes. Today tow ratings are standardized by SAE J2807. The Maverick has way more power than the old Ranger and weighs about 600 lbs more, plus it has trailer sway control. You're going to have a much easier time towing 4000 lbs in the Maverick than the Ranger.

Edit: The Maverick also has 300 lbs more payload capacity than the 1984 Ranger. The fact is, not everyone needs a giant heavy truck. I see loads of tradesmen driving Mavericks.