Maybe I'm confused about what you mean by primary and secondary sources, but I think you have to be a little more nuanced; otherwise, it sounds like you're advocating for reinventing the wheel ad vitam aeternam. As opposed to "standing on the shoulders of giants" and all that.
For instance, I would consider a literature review a secondary source. It can come to some conclusions as to the credibility of a hypothesis given all this presented evidence (primary sources). This can be very precious work, as it would save a person interested in higher-level topics a great deal of time, and most likely (if the review is any good) be done with more competence than the interested person has (amateur or not).
An amateur (or indeed a professional) is more likely to find pertinent information in existing "secondary sources" (which can also be plural) than by trying to comb through a comparatively enormous volume of primary work they are not equipped to interpret and synthesize (or even find). Not just in my lazy opinion, it's indeed the consensus in science that the most recent review/synthesis work is a good starting point to any background information collection.
And why not, as a starting point, have a tertiary source point you towards adequate synthetic work. When you type "my topic of interest review" on google scholar and pick the most cited moderately recent review of the topic, are you not in effect relying on a tertiary source?
I think those are essential things to do and valuable regardless of what else someone does. I do them myself all the time. I think the literature review is an amazing tool - really the best tool for learning, IME - and one that most people in the world (outside the research community) overlook.
Here we are talking about research in the science sense; those aren't research. You couldn't publish a literature review as 'research', for example, or get a Ph.D. for one - 'here's my dissertation topic - a lit review of ...'!.
There is lots of actual potential research for citizen scientists to do. And if they want to just learn from what's been discovered already, that's great - I certainly do that.
I think it's important that people understand that reading a textbook or secondary source isn't scientific research. Confusingly, now that I think of it, if you say 'I researched which EVs have the range we need', people assume you did not do actual research of driving them all. But that's a different meaning for the same word.
For instance, I would consider a literature review a secondary source. It can come to some conclusions as to the credibility of a hypothesis given all this presented evidence (primary sources). This can be very precious work, as it would save a person interested in higher-level topics a great deal of time, and most likely (if the review is any good) be done with more competence than the interested person has (amateur or not).
An amateur (or indeed a professional) is more likely to find pertinent information in existing "secondary sources" (which can also be plural) than by trying to comb through a comparatively enormous volume of primary work they are not equipped to interpret and synthesize (or even find). Not just in my lazy opinion, it's indeed the consensus in science that the most recent review/synthesis work is a good starting point to any background information collection.
And why not, as a starting point, have a tertiary source point you towards adequate synthetic work. When you type "my topic of interest review" on google scholar and pick the most cited moderately recent review of the topic, are you not in effect relying on a tertiary source?