Allocating and drawing down a meeting budget pool might assist with this.

As a positive incentive, a countering "attending" pool, also budgetable. Meetings with strong appeal would be compensated from that.

Not sure what to do with the Imaginary Meeting Points at the end of the year, though possibly use it as the basis of some sort of merit award or bonus.

At a bare minimum, teams that plan via "story points" or other time units ought to count meetings in those scores. When they don't, you start getting teams that either "get nothing done" or have to work nights and weekends because planning meetings are displacing all their intended work.

For actually tracking Meeting Points, one option might be to make them a project metric? As in: "We predict our project will consume 21 Meeting Points, if we go over 25 that's a failure to be analyzed afterwards like overruning schedule or budget, if we're under 15 we're probably budgeting wrong".

And I thought a few extra vipers was bad! I can't even imagine the level of ensuing bullshit...

Properly designing incentive systems in a realm of pervasive externalities and nonobvious costs and benefits is difficult.

I'm not saying the market/cost approach is necessarily the best or appropriate. But it's an interesting thought experiment to work through it.

Sometimes imposing arbitrary requirements (e.g., "have an agenda") is a cheaper way of effecting the same ends. Though Goodhart's Law is another pitfall.

NB: "vipers"?

I'm not certain it is a good idea to to that but let me try to come up with a more constructive way to do it:

Of course people shouldn't pay to do their work, so this must be taken from their allocated budget. If they don't have a budget they cannot invite anyone without the permission of someone who has a budget and think the meeting is a good idea.

in contracting this is not uncommon. one employer I worked for bid on a contract that was later revised down by 75 percent. meetings were curtailed to save money precisely because of the cost to the customer. budget sensitivity is a valuable tool to fight time wastagement.