It depends on who has the largest amount of influence on how noisy the on call is.

If engineers have blanket control to define what is important enough to get interrupted and to prioritize fixing frequent offenders, then sure, it's a perverse incentive.

If, on the other hand, engineering doesn't have very much control over the roadmap and/or isn't allowed to make their own judgment calls about what really matters for pages, then the arrangement that OP describes makes a ton of sense—it gets gets pages onto the budget as a separate line item, which is a good way to get the people who are really in charge on board with investing in permanent fixes.

It also becomes a good deterrent against useless requests. You get pinged on Slack at 10pm? Just ask them to file a ticket with a page-worthy severity. When its not nearly as important as that, even external managers will hesitate to do that since they need to explain if the ticket was worth 150% base pay for 3 hours plus the extra PTO next day.

Significantly reduces the number of pages.