In the modern world, the work of our bleeding-edge scientists and engineers is merely the tip of the stupendously vast iceberg that is modern civilization.
In a modern society, everything is so interconnected that any product is the result of that entire society. People who put products together, people who got the materials the products are made of, people who run the machines that generate the power required for those things… et cetera. Even the things people tend to forget or disassociate with the production of a product: people who write the manuals, people who act as “gofers” for all the other people, middle-management, etc.
Then consider all the people behind the construction of the tools required to do each of those things, and then who make the tools required to make those, and so on, and so on.
Now, suppose a large majority of mankind were to be suddenly wiped out? There would be huge holes in the knowledge of how to produce things. Sure, someone might know how to fix the engine of a car, but if there’s no one who knows how to make spark plugs, one is forced to hope they can find workable ones in the debris left After the End. And then there’s the need for gasoline. And oil, and tires, and antifreeze and batteries, and… well, you get the idea.
And even if someone does know how to make those key components, all that knowledge is little more than useless trivia if the infrastructure of society has been disrupted to the point that the raw materials can no longer be supplied. This is especially true if the power grid has been destroyed, since most modern manufacturing processes require extensive use of computers, power tools and precision that no human hand is capable of.
In the world of Phoenix Point, 90% of the human race is dead. Independent havens are going to be far too busy just surviving to even think about inventing a new and better type of ceramic. Spending the effort needed to R&D armour that is 5% better will just get you killed by crabmen - you need to spend the effort the scavenge existing armour and bullets, and _maybe_service the cars and guns you already have.
The only exceptions are the major factions, each of which planned for the apocalypse in some form. But even there, I would expect progress to be limited - NJ is focused on better ways to kill stuff, the Disciples are tinkering with Things Man Was Not Meant To Know rather than doing actual science, and Synedrion…Synedrion actually does make substantial improvements in technology, I’ll grant you that. But they have…other problems.
Bottom line: for the most part, people in a post-apocalyptic scavenger world will value the people who can machine guns and can keep cars running. Not the university scientists whose research depends on a vast industrial/technological/knowldege base that has simply stopped existing.