It makes it really easy to add the tablespoon of detergent to the tub for the prewash as well as the needed dose for the dishes (which is really not much unless you have it loaded with greasy plates)
Technology Connections on YouTube has several relevant videos
The dissolvable packets of a dishwasher detergent are very different than the forever microplastics that people are worried about. Those are designed to be durable and last while the detergent pods are made to dissolve.
That said the powder detergent is great and SO much cheaper per wash. Also you can put some in the prewash for better washing.
The microplastics issue is more contentious, and while many say it’s bad that it enters the water supply, I suspect the smallest of the particles do not wash away so well
It's not the microplastic people are concerned about but it's a plastic that sticks around in the environment and bioaccumulates.
There are properties we're good at designing plastics around like hardness, stiffness, and environmental resistance. But there are properties we're very bad at designing plastics for decomposition, especially alongside niche other traits like water solubility
Target has a store brand detergent that works well. But I find it's easier to use too much with powder. Compared to gel, It's harder to control the pour, and if you have too much it leaves a residue.