Connecting Amazon Seller Account to your Seller Assistant account gives you a lot of advantages. Doing so you can:
use Bulk Restriction Checker tool
see product restrictions in Price List Analyzer tool
see product restrictions in Seller Assistant extension – feature "Brand Gate"
get the data about the product directly from Amazon servers
avoid some errors from appearing e.g. Offers Parse Error, Fees Parse Error, Product Parse Error etc.
Connected Amazon Seller account also speeds up loading of the extension on product pages.