Buying home and away memberships shouldn’t come with points, there’s no argument for it whatsoever.
If someone is in the higher points brackets, why should that be eroded because someone else who doesn’t go as often spends £30 or £50 or whatever it was. Over 3 years that could significantly impact their relative position, not least because they will be having more points dropping off in future years.
Only fair way would be if ST holders got no points for home memberships and away memberships gave no points at all.