Martin, you are just too young to remember dryers without lint filters! If you look at an old Sears Roebuck catalog, in the accessories section for washers and dryers, you will see lint filter boxes that could be added to the backs of dryers at the exhaust port. Early WH dryers needed these and while the slant front machines eventually got that little hatch on top to house the lint filter, the old Space Mates dryers with the window in the door never had a filter. There are probably others. The WH-made combo that Wards sold was the vented machine, but it lacked a lint screen. It just spewed lint outside, giving a year-round flocked effect to any vegetation near the vent. Maybe it helped people keep Christmas in their hearts all through the year.
We have had posts here about the Kenmore dryers with the lint storage systems. They used a little paper bag like a vacuum cleaner bag with a window in it to store the lint that was separated out of the exhaust air stream by a centrifugal separator. Whirlpool is big on centrifugal separators. They used one for dryer lint in the first 29" combos, in the Power Clean dishwasher module and more recently in the lint storage dryer they brought back briefly, but people thought you only had to empty the lint every 100 days or something stupid because of the logo on the dryer. When they discontinued it, they said it was because it was too noisy, but really it was because most people are too stupid to cope with lint unless they see it. One of the good things about GE's up front lint filter is that people are forced to deal with it or they get lint all over their clothes as they drag them out of the dryer.
Our hamsters and gerbils loved dryer lint for making cozy nests. Mom would not put it in their cages, but she would save it for us to add.