I take your point about big 6 tourists! In my case when I have bought the odd ticket for other people, they have been friends who aren't followers of any specific club, or simply want to savour the experience of being at the Amex and watching Premier League football.
On the other hand of course, and this isn't my opinion, but evidently the opinion of the club, many of those seats bought by season ticket holders will be occupied by potential 'new' Albion fans, leading long term to even more revenue for the club.