@kirkjmiller - I agree with you, this is ridiculous that QBO still hasn't resolved this.  Their work around doesn't work and vendors continue to be added.  I created a work around to avoid having a bunch of random vendors added that I don't want or need.  It's unbelievable that we have to create a work around for an issue that QBO is aware of and doesn't fix, but that's the way it is.

To avoid having vendors added that you don't want, create a faux vendor profile.  Such as MISC Vendor- Due to QBO.  Then, from your banking feed, anytime a transaction in the feed shows it is going to add a new vendor, just change the vendor to the faux profile you created.  Then at the end of each week, my AP clerk opens each of the expense transactions with the "MISC" vendor and deletes the vendor from the expense.  With this, you control if a vendor gets added.  Yes, it's more steps, but it still leaves us in control of who is added as a vendor.  Hope this helps.