It was tried, quite extensively, early on in the reprap movement. No-one managed to get it working reliably. The issue is that the pellets don't feed consistently enough. This means the flow is inconsistent. This massively messes with the quality of the print.
There are theoretical ways to compensate. Unfortunately, most result in a huge jump in complexity and weight on the head. Neither is a good thing.
Basically. The benefits aren't generally with the costs, outside of a few, very niche areas. It's also now easier to source filament most places, compared to pellets. So even that isn't a game changer.
Pellet printing is usually used in larger printers. You can get much higher flow rates and the pellets are cheaper than filament. That's good when your build volume is measured in cubic meters and you are using many kilograms of plastic in one print.
There are downsides as well. High throughput pellet feeding hot ends are insanely expensive. But there are practical issues as well, retraction can be really tough to dial in.
he does say you can do chocolate. apart from the hot end, auger, and mechanical parts it's all 3d printed though. I guess you could go through the cursed endeavour of setting up an all stainless printer to print all the parts in one of those so called food grade filaments but I don't trust that much. Or you can just operate off the understanding that we are all saturated in plastic already.
You would be giving up some feed-rate control and retraction. Probably not too bad with certain materials and large scale prints, but I'd be surprised if you could do anything moderately precise with this.
You want to minimize wight and vibration on the printing head. And everything that deals with pellets adds a great deal of both.
In theory you can manage to melt the pellets in a static machine away from the printing head. But you will get a lot of new problems getting it where you need and switching it on and off as needed.
Pellet feeders are not meant for high speed machines. Pellet feeders are for large format machines where the speed comes from the volume of filament they can extrude while printing.