Shadowbans help prevent bot activity by preventing a bot from knowing if what they posted was actually posted

I have not seen anything to support the theory that shadowbans reduce the number of bots on a platform. If anything, a sophisticated account run by professional engagement farmers is going to know it’s been shadowbanned - and know how to mitigate the ban - more easily than an amateur publisher producing sincere content. The latter is far more likely to run afoul of an difficult-to-detect ban than the former.

It wastes bot’s time

A bot has far more time to waste than a human. So this technique is biased against humans, rather than bots.

If you want to discourage bots, put public metrics behind a captcha. That’s far more effective than undermining visibility in a way only a professional would notice.