Every rule has exceptions. Usually its because of some quirk of the market. The most obvious example is adtech, which is able to sustain massive margins because the consumers get the product for free so see no reason to switch and the advertisers are forced to follow the consumers. Tech in general has high margins but I expect them to fall as the offerings mature. Companies will always try to lock in their users like aws/oracle do but thats just a sign of an uncompetitive market imo.