> Users may have the file pre-cached

This is no longer true. Due to security concerns browsers no longer re-use the cache between websites.

That said, hosting assets yourself is fantastic if you use a CDN. Accessing American websites without CDN from Europe can be quite rough. I remember one of my first remote freelancing gigs where it took about 5s to load the company’s website hosted on Heroku. Just because of availability zones.

At my current gig, we self-host our assets and it’s fine because we’re US-centric. We host in us-west-2 and I live in SF and everything loads super fast. But you can really tell the dev site loads slower when working from the east coast.

Network latency is no joke.