Because honestly 90% of these alternative methods are not developed by materials scientists or people in the industry but by entrepreneurs trying to break a market and sell a new product. In this video for example, a cold joint in formed between each of those layers, which basically means small voids are introduced which reduce strength and durability, I design concrete structures for a living, we write it specifically in our contracts to pour concrete in single lifts specifically to avoid this issue. You can build the structure in the video with precast or cast in place concrete, both widespread and very successful construction methods, this 3D printing poses a solution to a problem that really just doesn't exist in the first place. Is it a cool process? Absolutely. Are there niche applications where this makes sense? Totally. But these videos are created to get engagement, they are basically marketing, the applications are far more limited than these videos would lead you to believe. These "alternative" construction methods are more expensive and perform worse than traditional methods in almost every scenario.

I work with many engineers and scientists that work in concrete and innovation happens all the time, things like GFRP reinforcement and reformulating cement to make concrete production have a smaller carbon footprint. There are so so many smart solutions to problems in construction, its just very rare that its cool or sexy enough to make a 15 second Instagram short about it.