I think it has to do with many people in the forum are new to van dwelling don't have the skills and/or tools to build or design complex beds that have multiple functions. They really just need/want something cheap, simple and fast.
But it is simple enough to do if you have some woodworking skills and the physical space. You need two hinged areas, one under your knees and one for creating a back rest.
There are a number of schemes for making the sections adjustable. There are motors/cranks and there are notched racks. The notched racks are possible but rather a nuisance for daily use in a tight space.
But take a look at this video, it is basically pieces of plywood on a steel frame that are activated with threaded rods with hinged arms.
It does not matter if other people are doing it. What matters is are you yourself capable of creating an adjustable bed or could you purchase something that will fit into your, budget, space and weight constraints? There are lots of commercially made models around.
I have been sleeping on a twin size, motorized, slat bed from Ikea for the last 10 years. But they quit selling them in the USA quite a few years ago. I thought about putting it into my RV but it would not fit into the space without modification and it is older so who knows how long the motor would last.
.cut foam matress with an electric carving knife
