The term "Conspiracy theory" seems to be a language construct that is meant as a weapon to prevent poking at real conspiracies. See the following quote from Conspiracy theory as heresey

Whenever we use the term ‘conspiracy theory’ pejoratively we imply, perhaps unintentionally, that there is something wrong with believing in conspiracies or wanting to investigate whether they’re occurring. This rhetoric silences the victims of real conspiracies, and those who, rightly or wrongly, believe that conspiracies are occurring, and it herds respectable opinion in ways that make it more likely that powerful interests will be able to get away with conspiracies.

It's a very insidious use of language, and the comparison to heresy is apt. We probably need a different term to differentiate between low-status-silly-conspiracy-theories and serious-minded-conspiracy-theories. Just like there is a difference between alternative medicine and medicine. The issue is that this term is so popular that it will be very hard to spread an alternative term and explain that some conspiracy theories are valid. What makes it even worse is that people in power love that term. It definitely serves their interests that trying to analyze their conspiracies has an immediate, easy rebuttal, such as saying ironically, "That's a very interesting conspiracy theory." And that's true for all the people in power. It doesn't matter what their ideology is.

In a way, it's a stable memetic attractor that always serves the interests of the group in power - which can explain why it will be hard to get rid of. However, it's obviously manipulative in an Orwellian way.