This isn't a great answer to the overall issue (which I agree is a ridiculous dark pattern), but I've used Privacy.com cards for personal projects to hard spend at a card level so it just declines if it passes some threshold on a daily/weekly/monthly/lifetime basis. At work, I do the same thing with corporate cards to ensure the same controls are in place.

Now, as to why they're applying the dark pattern - cynically, I wonder if that's the dark side of usage/volume based pricing. Once revenue gets big enough, any hit to usage (even if it's usage that would be terminated if the user could figure out how) ends up being a metric that is optimized against at a corporate level.