For any two given planets in the galaxy that could support intelligent life, in all likelihood the technological progress of those lifeforms will not align, and it won't be close. Imagine one civilization encountering another, except the first is 50,000 years more technologically advanced. Or 500,000 years. Or 5 million years. What would happen?
The more advanced civilization wouldn't be playing games to keep from being discovered, that's for sure. They wouldn't care. Even visiting the planet would be a total waste of time since with that level of technology they could certainly observe from afar.