I'm not very qualified to speak on the subject, but Svelte had (last I checked) the feature of not having a VDOM, meaning I was able to use generic JS libraries with it that did not require a implementation that was Svelte-only, as is the case with many such React and Vue libraries.
Personally, I like to stay as close to web standards as possible, instead of tying myself to specific implementations of specific addons for specific frameworks.