The lack of support is in the other direction - Safari doesn't support uBlock Origin anymore. The only way to block ads is with Apple's Content Blocking API, which is fundamentally not how uBlock Origin works.
Safari lets extensions precompile a list of patterns to block and then it does the actual blocking. The extension never sees your browsing history or network requests.
Safari also has a limit, and it's low enough that plugin developers have had to split their work into multiple parallel plugins or even into standalone macOS applications.
uBlock Origin uses the WebExtension API that is common to Chromium/Firefox. Going forward, Safari for iOS/macOS will only support Apple's Content Blocking API.