The most simple, straightforward, and concise way is my least favorite word in the world: metrics. By using X, you increase the amount of activity on the platform, which the Muskrat takes to advertisers and investors and says "Look how many people use my platform, you should be paying me more money for access to the value they have as consumers/data to harvest."

This is actually why they made that ad-blocker that clicks on every single ad it blocks that I can never remember the name of. Because it financially hurts both the company serving the ads and the advertisers themselves as well by both messing with their data on you as a consumer (they can't add your interests to a group to sell to advertisers if you just click on everything) and by hurting their click-through to sales metric. Their click-through rate goes up, but because their purchase rate doesn't, it makes the metric go down and makes them less willing to spend as much on an advertising spot when they're less likely to get a return on that money.

There's also that whole thing where people go where there's a lot of people and by being part of the group that keeps people there, you're exposing them to right-wing propaganda and the various disinformation bot campaigns and whatnot, but that's a lot harder to explain/messier to get into.