This isn't always true. Sometimes you want to stop large customers from performing naive cross-comparisons of price when the on-the-ground reality is more nuanced.

This can be price levers on individual features, security track record, non-obvious user patterns that deliver a lot of value, etc. You're given more opportunities to pitch the full value of your product in a way that engages the customer with their particular pain points.

Maybe we should still all use transparent pricing, but I don't think it's fair to say it's used to extract more cash (though some companies definitely do that).