I think this is absolutely true. My OCD was minimised greatly by treatment, but I am still prone to returning to certain patterns and have to put in active work to maintain my current state

Depending on whay you mean by "cure". Maybe there is always something left, but you get better at handling it over time, which is way better than getting completely lost and spending all your time and energy indulged in the obsession and your own fantasy.

Technically you’re right, but it’s like some antiviral therapies—technically the virus is still there, you are on pills forever, but your quality of life gets soo much better.

You cant erase a memory, once you have it you have it. This means that no matter how many other memories you add too to morph and alter the original, the original will allays be there in one form or another.

But people can go from debilitating OCD (meaning hours a day), to a state where they only think about the thing once a week. It might (and probably will) poop up later in life but even so with such a difference i would call that cured.