This is a popular sentiment on HN, but it oversimplifies the situation. Engagement, in the aggregate, does not pay the bills. Advertisers paying us to sponsor tweets does. Advertisers will only do that if paying to sponsor tweets results in either improving brand image or converting sales.
Advertisers won't pay for ads that don't get clicked on. Political pissing matches and disinformation campaigns don't bring the kind of engagement that results in clicking on ads and buying things, or of making positive brand associations.
Engagement costs us money. It increases system load and the resources required to actually run the platform. Raising engagement for the sake of raising engagement is a net negative in the long run, because it results in too much engagement that doesn't sell products (and thus ads).
I suspect there are some here who won't believe this; a few may be tempted to throw out a certain pithy Upton Sinclair quote. I'd like to know from this camp why you think that way.