Spam bots have a preset spam limit. Knowing their weakness, we can send wave after wave of mods at them until they reach their limit and shut down.

Exactly. This is only a “stupid” decision if your only metrics for success are unmitigated growth and content/comment quantity.

Yes, for a community to thrive there needs to be some minimum viable threshold of active participants, but that threshold isn’t “as many users as we can possibly get.” Just like there’s a bottom limit, there is a sort of carrying capacity as an upper limit. Out of control population growth will quickly make an ecosystem inhospitable which will kill a community just as surely as not having enough members to sustain itself.

I agree with this. One of the more irritating things about places like Reddit is that they’re full of low effort content and conversations get filled with a lot of noise from people who don’t really want to meaningfully contribute.