I don't think the platforms are providing the bots. Platforms have the objective of increasing engagement.

Bots are being used by people, organizations and governments with goals. Usually, effectiveness is increased with more exposure, so their goal of gaming the platform algorithm to maximize engagement with their content aligns with the platform's broad objectives.

But the motives and actors are separate and distinct.

Think of the bot content as the payload, and the platform as a vulnerable service that is being hacked.