Merchants and promoting hearthlings?

So i have been noticing that when ever i promote a hearthling to weaver the merchant that comes next will always be the one with clothproducts… i think its the same with the mason?
Why is this? why do i need to buy cloth products the moment i now can produce them myself?
Or is that merchant locked in some way before you get a weaver, just so you feel you need the weaver?
I am playing as ascendency, i dont know if this is the same with RC?
Basicly i just promoted the hearthling to get two banners for the blacksmith forge…not the armor…since i have the blacksmith!
In my view the weaver is completely useless and have no real function other than getting rid of silkweeds and fleece…

Weavers are mostly aesthetics for me, personally, but I believe the merchants are at-random.

Well, my weavers are usually busy making the threads, cloth, and leather that other crafters use, as well as the mentioned banners/flags and decorative carpets and panels.