I believe we get derailed by thinking about search engines instead of visitors.
1. Starting with an idea of creating a website to create income is wrong.
2. Starting with an idea of creating a website to promote ideas is right.
In other words, in 1., thinking about topic for a website that will carry ads, be optimized for search engines, etc. is wrong.
For 2., if I play a guitar well, and I start sharing that knowledge via my website, that's right.
From the above, instead of thinking without Google, why not think without any source of your future traffic?
Pretend you're a guy that has no clue about how web works. Yet, use your existing knowledge to create a good website (forget SEs, optimization, etc.).
This was just a thought initiated by OP's initial post.
I create websites with affiliate business as a main model and after 8 years, I even today have a hard time to think outside of the box. I'm sure I know all the theory needed for the success, but when it comes to implementation, I fall short.
You have to live stuff in order to have quality.
I.e. how can I promote some software as an affiliate if I have not used it to a great extent, and documented everything well? And I have to do that for 10s or 100s of software products in order to be unique and successful. How many websites do this out there? Not many, and I believe they can be counted on fingers of one or two hands.
If folks find a website useful, the rest will follow. Yeah, it's about right order in which SEs come later on.