Consider the value of your comment:

To someone with no knowledge about your claim (me included), it seems like an extraordinary claim with no extraordinary evidence, or really any information at all, to back it up.

To someone with knowledge of your claim, assuming it is a true one, it adds nothing to what they already know. So maybe it's obvious to an expert, but then they don't need to be told.

I disagree. I think statements like that can capture people's interest and spur them on to look into it further on their own. It's kind of a reminder that X exists.

got any sources for that? I would think that any credible, conclusive evidence of nootropics actually doing anything would spur a great deal of fanfare

They do do something. Caffeine is a nootropic that has well studied positive effects.

The thing with most nootropics though is that the effects aren't big, the side effects of chronic usage aren't well known, and the basics such as exercise/sleep have a bigger effect.

Out of the two mentioned above (magnesium and l-theanine) - many people are deficient in magnesium due to modern diet, and there's some evidence that l-theanine works well with caffeine to aid concentration (it's found in green tea but not coffee). I have no idea about the neurogenesis claims though.

Does lithium count as a nootropic?

https://pubmed.ncbi.nlm.nih.gov/15581403/

https://www.neuroscience.cam.ac.uk/publications/download.php...