Advertisers, presumably. Not in marketing, but I suspect platform engagement is a primary driver for gauging advertising value. Bots are perceived as a way to keep people engaged even with activity down, or if they're engaging in a largely detestable way. It's a sad product of perverse incentives.

That'll inevitably change with time and audience dilution. But for what it's worth, I don't know if that's necessarily a bad thing. We've come to expect a mass-appeal homogenization of digital communities, but in theory it's probably healthier for there to be a diversity of social atmospheres.