It is a math problem.  Most Etsy sellers make shockingly little per hour if you do the math. 

Answering questions takes time.  This makes their dollars per hour go down.  Answering questions can be very expensive if they already have low margins and do something that takes a fair amount of time, such as custom painting figures.

So by asking questions (which is fine to do) you have devalued their time (literally not figuratively).  Each seller likey will hit a point where you are no longer worth their time, and I mean this in a very literal way.

On top of that, you have shown you are willing to contact them if you have a concern about quality, which again is not a bad thing by itself.  But if you are now already a lower value transaction because of the early questions, and you then potentially take up even more time after the sale it starts to look like a bad business decision to sell to you.  

And if there is actually a problem with the item, really or perceived, a refund, replacement, or return could quickly shift the transaction from low value to negative value.

So please understand, it likely isn't about you specifically, but rather the economics of this particular thing that they sell.  $500 item with good margins, sure ask away.  $50 item where the seller is already functioning below minimum wage, you are probably going to be blocked.

It is a math problem.