Not sure why you are blaming eBay for this, they have not blocked you, they are only a selling platform, the seller has blocked you.
I can only guess, and it's only a guess, that you are trying to buy an expensive piece of furniture from this seller, and seeing you have no recent buying activity, perhaps this made them block you.
I agree, It's not a good reason to block a buyer and it may not be the reason, but it's the seller's prerogative, to block anyone they do not wish to sell to.
@nichni_40