Sure, I’ve been doing that since the 90s. I still pay for hardware and egress, and it turns out that everything has limits for the amount of traffic it can handle which bots can easily saturate. I’ve had sites which were mostly Varnish serving cached content at wire speed go down because they saturated the upstream.
It is on a simple WordPress install with the top 4 most used plugins, when you don't have a Caching Reverse Proxy like Cloudflare to filter bad traffic and serve fully cached pages from POP nodes located near the visitors.
The alternative, of course, is to set up a caching system server-side (like Redis), which most people who set up their WordPress blog don't have the first idea how to do in a secure way.
