perhaps interstellar travel is impossible or maybe civilizations are always self-destructive. But with every new discovery of a potentially habitable planet, the Fermi Paradox becomes increasingly mysterious.
No, it doesn't. It just suggests that interstellar travel and communication are very, very difficult. They don't have to be impossible, just hard enough to put a spoke in the Ponzi-scheme galactic colonization plan that the Fermi prediction relies on, and why SETI hasn't found any needles in the haystack yet.
We know that space travel is hard. We got from powered flight to landing on the Moon in a single human lifetime, then hit the wall. We have hugely successful, experimentally proven theories of physics that say that FTL travel is impossible, and well-reasoned scientific speculation showing that the possible loopholes (Alcubiere warps, wormholes etc.) require access to exotic matter, consume ridiculous amounts of energy, and (fortunately, for causality's sake) have deal-breaking complications... and even if they work may only provide near/at/slightly over lightspeed travel. We know enough about energy and matter to start doing the sums for slower-than-light interstellar travel and work out how difficult it is* (even SF writers fall back on Unobtanium power rather than 'old fangled' fusion drives for their generation ships, now).
As for communication/detecting signals, our only data point is us: A century or so after inventing radio, we're already switching to highly compressed, encrypted digital signals indistinguishable from noise without the 'key', transmitted at the lowest power and tightest beam possible.
So, despite all the plausible resolutions of the 'Fermi paradox' which, while not proven, are built on reasoned extrapolation of what we do know, why do people focus on the least plausible resolution: 'there are no aliens' which, while impossible to conclusively disprove without actually finding an alien, relies on us existing on the tail end of a probability curve?
That is anthropocentric thinking bordering on religion.
* Plus, if you can build generation ships that can survive in interstellar space, and manage their populations, it would be far, far easier to build space habitats and park them somewhere with solar energy and big chunks of raw materials floating around. Kinda reduces your incentive for Ponzi colonization which, as Greg Egan put it, "is what bacteria with spaceships would do".