I'm a Systems Reliability and DevOps engineer for Netdata Inc. When not working, I enjoy studying linguistics and history, playing video games, and cooking all kinds of international cuisine.
You can actually do custom versions of the assets. Bootstrap is probably the best example of this, as Bootstrap 4 pretty much requires you to have your own custom version of the CSS if you want a custom theme (and it looks like this probably won't change in Bootstrap 5, but might in Bootstrap 6 if they finally start using custom properties).
You aren't dependent on external infrastructure. Remember what happened recently when CloudFlare had issues?
You don't have to worry about leaking customer information to external sources. This sounds stupid, but may matter in some cases.
You can easily develop your site offline. You might be able to do this still with a CDN, but you have to be lucky for it to work, and also have to remember not to use a hard refresh.
Arguments in favor of using CDN-hosted assets:
If it's a common asset, the client system may avoid making a network request.
Even if it's not a common asset, it's less disk space and network bandwidth needed for your server.
Also, note that both arguments favoring CDN hosting become a bit weaker if you're doing a PWA and your Service Worker is sanely handling the caching.
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
Arguments in favor of hosting your own assets:
Arguments in favor of using CDN-hosted assets:
Also, note that both arguments favoring CDN hosting become a bit weaker if you're doing a PWA and your Service Worker is sanely handling the caching.