Also CDNs became cheaper and easily accessible. They don’t eat anywhere near 100% of your traffic for most sites but it’s likely enough to get a big chunk of the cacheable traffic at lower latency than your own Varnish server can unless you’re running them all over like Fastly. If a significant fraction of the traffic coming back isn’t cacheable the benefits of running Varnish might sink below the level where it’s worth dealing with another layer of production infrastructure.