What's the point of making a landing page with more than 1 file?

Question

HTML

Does it make sense to make one-pagers, not 1 file. 1 file means to embed all styles, all scripts in html, and even insert pictures and fonts in base64, that is, to reduce the number of files as much as possible.
When even 2 pages, it is clear that the cache plays a role, but if there is 1 page, then there are no common files, and the page itself will be cached.
Naturally, all this will be done by the collector, and in the source code everything will be on the shelves.

Answer 1

Depends on the size of the landing page.
You seem to want to optimize the loading, for this
1. all styles are inline in the head without including files
2. scripts in the footer with files
3. always load pictures on the first screen, everything below the first screen is lazy load
4. use google page speed and his recommendations, they will immediately tell you what you are doing wrong and why.
5. use cache.

Answer 2

The idea is good, only the execution is long, and the browser in a small number of threads will load up to the limit of the RAM.