This feels more like the old "progressive enhancement" model than the full blown SPA style that's popular today. Most navigation on Wikipedia is plain old brow

This feels more like the old "progressive enhancement" model than the full blown SPA style that's popular today. Most navigation on Wikipedia is plain old browsers loading HTML pages, but if you happen to support JavaScript, it's used to augment the page to make it a little easier to browse. (I don't actually know for sure whether Wikipedia pages are primarily server rendered, but what you describe is perfectly possible using progressive enhancement).