Since I myself was just hit by something like this…
I’m very happy for Alexa to be able to use my site content to answer questions, so I don’t really want to block it. However, I just saw a burst of three days of heavy traffic from AmazonBot (relative to all other site usage, including all other bots combined, as well as all other site traffic overall), and I see that Amazon says:
AmazonBot does not support the
crawl-delaydirective in robots.txt
It seems like it is prudent, therefore, to add Amazonbot to slow_down_crawler_user_agents so that they do not have an outsized impact on site performance for users.
Thanks, Discourse folks, for implementing functionality that crawlers ought to, but in this case do not. 