Never heard of them. Can you link to the article?

I'm familiar with soil cubes but would never use them. I grow too many annuals and perennials (1000s) over the winter for over three months under lights and need something stable. Cell packs work best for my purposes.

Here is the link to the original article.

https://www.seattletimes.com/pacific-nw-magazine/want-to-eliminate-all-that-plastic-in-your-garden-learn-how-to-create-soil-blocks/

I am not sure how this can eliminate plastic in the garden, because we reuse our containers for years. The photo in the article shows plastic - the sheet type - under the soil blocks. Every reference on-line put the cubes into wood or plastic trays so they can be safely moved. But that is my take on them.

I have had some success with this tool, and there are YouTube videos of people doing this at some scale. https://www.gardeners.com/buy/soil-block-maker-4-cell/8599790.html 

Honestly all it really is is a set of little blocks of potting mix in a tray or container of some sort. The size of the block is maybe very roughly about 10-20x the size of the seed. Make a little indentation on the top where the seed goes.

It is nice not to have to use plastic, but as @ophoenix points out many of us can reuse the plastic pots we already have for years.

For me the benefit is that if a seed fails to germinate, my little marble-sized "germination block" (for those carrots) is easy to toss in the garden. If it does germinate, you simply add the small block to a bigger block.

Hope this helps somewhat...