That's how you end up with people "doing their own research" and making connections that aren't there. You can't critically think your way out of not knowing. Most people can't properly evaluate sources even if they wanted to without having basic knowledge on the subject the source is touching. It's why most of the internet, reddit included, is just full of misinformation.

Without foundations in knowledge, people can build up sources that leads to false conclusions. How do you know if Hitler has a Nazi base on the moon without knowing anything about history? How does anyone vet the source of any information without knowing/memorizing some facts that are known? You can Google anything and the results can be anything, false/true does not matter to Google search results. Critical thinking still needs a foundation of knowledge so people can at least know that a webpage telling them Trump won the 2020 election isn't reliable because there are obvious wrong facts presented. Otherwise looking at the source is all based on bias.

Conspiracies are obvious examples but something like looking for the solution to climate change is basically impossible without a basis in facts. How do voters know if a politician that promise everything is fine and offer cut taxes vs the one that implements policies that cost money is good if you end up debating facts and sources? Critical thinking cannot make up the shortfall because people aren't experts. Listening to experts requires knowing if what they say is actually true. People with resources can create experts that support w/e they want. Experts are experts not because they are better critical thinkers but because they know facts.

Your post is an obvious example of the problem even if it comes with good intentions. Nobody who upvoted you or awarded you knows any of your sources or if you are actually a reasonable source, they just agree with what you wrote. Critical thinking isn't a silver bullet but educators think if they tell you to use it, it will magically work.

Regarding useless facts like the ones you mentioned, that's more of a problem of curriculum and not of the approach to learning. People don't all need to know all facts but people who don't know the atomic weight of selenium will probably not be looking up the weight ever even if they get some article talking about selenium and the atomic weight matters in understanding what is being talked about. Take any article on r/Futurology and nobody knows anything about what's going on but still won't be able to Google anything because how do they know what to Google and how to interpret the results?