There are blocks with category or we can say Types, Examples are dirts/sands/planks/wool/stone/clay and when lets say, we create a custom plank
An option to make the block go into Planks category so it can be used as plank for all crafts that requires wood planks, It also depends on Other mods which uses planks in their recipes so we can use our Custom plank in their recipe
same thing for saplings(still waiting for trees improvements)
Also for item type, custom items that can replace vanilla items, like dyes, leather etc...
i think you know what i mean
Oh and for stone, Stone is a category too, His category is Diorite, Andesite, Granite, which means that These blocks will always spawn with stone(sometime)
The way you proposed this will not be possible as for example Diorite, Andesite, Granite are subtypes of stone and you can't just add another subtype that is any block.
We have ore dictionary support in the plan, which will make more or less the same thing possible, but there is already a ticket for this (https://mcreator.net/tracker/issue/42517) so I am closing this one.