I find that the problems you mention are primarily a problem when you offer free accounts and monetize via some other (and typically malicious) way such as the

I find that the problems you mention are primarily a problem when you offer free accounts and monetize via some other (and typically malicious) way such as the usual "growth and engagement". If accounts or services are paid, spamming becomes unprofitable (the ROI of spam would become negative as they'd need to keep paying for new accounts all the time). Scraping? If you're selling content you should be selling content and not mode of consumption, and for misbehaving scrapers your DoS defense strategy (you have one, right?) would also work there - an easy solution is to rate-limit the amount of requests by account to a reasonable level (that a human user won't exceed) and then let them choose whether they want to consume the content manually or through scraping.