This assumes Google can't figure out crawling SPA.
Generally, when I'm building a business, I prefer not to assume that Google will eventually, at some point in the future, solve the crawling a SPA site problem and finally discover my site.
I'd rather get my 70%-80% organic search traffic today, with any boring server-side rendered tech stack.
Why people use js/spa/etc stuff as the basis for a content/marketing site... I don't know. I mean... yeah, I know why - mostly to expand their skill set. But there's usually no functional benefit, and usually some drawbacks, as you're pointing out.