A: I think it depends on your needs and preferences. I believe some customers who have done this mainly do it because they need or prefer some features or blocks that are not present in one plugin, but is present in another. This goes both ways, let's say you don't use the full extend of Kadence, and just use some features and use Stackable for the rest, of the other way around.

As for WooCommerce, we support WooCommerce in our Dynamic Content feature where you can pull different WooCommerce product data and use them in blocks like images, urls, text, etc. We don't yet support WooCommerce's experimental block editor for editing products, but mainly because of its experimental nature and looks like it doesn't yet support third-party blocks.