It is only when trying the Hello, Blockstack ! app that you are offer to sign in with blockstack (which will redirected outside of the blockstack browser). After clicking on sign in, you are again redirected to the blockstack site and it offer you to either install blockstack or to do a quick sign in.
To discount these network issues as being merely related to ‘spam’ is equivalent to a limited group of people adjudicating what the bitcoin network is for. Most importantly however, it is a dangerous game, with far reaching implications, for the industry or developers to begin declaring which transactions are ‘good’ and which are ‘attacks.’ If Bitcoin is to be an open network, central planning of what type of transaction is acceptable shouldn’t be acceptable.