Turbolinks and the like just move the problem elsewhere. Great, now your site is no longer blank on subsequent loads but your first input delay has jumped by a magnitude since the server still takes forever to respond. There's still a delay regardless.

Also Turbolinks only becomes useful after the page has loaded. So every fresh visitor is still going to see that horrible flash of blankness, wondering if the site is broke.

That isn't to say it's worse than just default server-side rendering: I think it provides a better UX. But who knows how much, and who knows if it's better than a SPA. Nobody is citing any real data here, just talking out there ass.