They are share commonalities because they're echoed through history though different motifs and myths and stories and legends. Then they're picked up and made to be "esoteric", "spiritual", or assumed to be beyond human comprehension. These people or groups are usually people who have money and want to find "a truth", but it was probably more honestly because they are rich they are "chosen". Enter, Bavarian Illuminati, Alister Crowley and those types of crowds (the founder of JPL was involved in such activities), et al (in my opinion of course). They all have symbols that date back to ancient times.

S1 had motifs of the pagan esque , religion and good/evil eg Carcosa and the Yellow King. S2 has commonalities more seen in urban or grandiose societies where the rich/powerful control aspects of society regular people cant touch eg corporations killing the trains in LA (huge swaths of money and influence needed to make it possible).

I get what you're trying to say though: people who have "inside knowledge" of people committing dastardly rituals, sacrifice, and pulling the wool over us regular people. But the fact is dude, these stories have been echoed through time memorial.

These things aren't new, people were always thinking up of the weirdest shit the upper class was doing. The upper class always thought they were chosen. We just see more of these things because: a. they are interesting. b. the medium of film, art, and technology can allow both access to understand and access to an incredibly wider audience than was possible before, hence more exposure. and c. these motifs, legends, urban myths and symbols all present sub conscious thoughts that are in the recesses of our mind (the supernatural, the evil etc).

The cult, occult, supernatural and such have always been a fascination with human beings ever since we had conscious thought.