Just my perspective. 1. Most startups do not have all the bells and whistles, so needs explanation or demo's or 2. They are in MVP stage. or 3. Founders either believe that their concept/design is intuitive or just they have not yet got to a stage where it is refined and becomes intuitive. or
4. Founders have not got the product in front of the end user yet.
I feel so because, every founder builds their product/service thinking that their startup concept/product is simple to understand and is intuitive.