I think your experience is unique to you only and does not reflect more widely on the rest of us with similar cards who have perhaps not gamed their system to quite the same extreme as you have. Just surmising with no evidence, but maybe they ran an audit that highlighted the customers who were the least profitable to them. ie. those who were maximising the benefits to an extreme, while at the same time carefully avoiding all costs and charges, and have simply decided to 'off-board' them with extreme prejudice.