Why? Just look how many species we have/had on earth and how many actually discovered 'technology'..only one. Sure some use extremly basic tools, but not one of them broke the threshold.

Some of them are quite smart, and what if they even had human intelligence like..say.. a dolphin. What's he gonna do? He can't create advanced technology, even if he wanted to, because thanks to evolution he's stuck with stupid flippers..

Maybe somewhere in the universe there are super smart talking space cows, that discuss philosophy. Nobody would know, because they neither have hands nor opposable thumbs. They're not getting anywhere and if a natural disaster hits their area, they're totally fucked. They'll never be able to do surgery, write thoughts down nor invent vehicles, that would allow them to travel to friendlier areas.

Just having basic life doesn't get you anywhere. Because a species needs to be successful/adaptable, intelligent, big/fast enough to get to the 'good stuff', 'hands'&fine motor skills. It needs strong social ties and invent key technologies like writing/reading, teaching further generations and the species can't be destroyed by a extinction event, whether it's a natural disaster, a horrible&violent disease or whatever.

For us, the next barrier is getting rid off internal conflicts and realizing, that we all sit in the same boat. There have been 4-5 situations in recent history were we almost nuked ourselfs back into the stone age. Just think about it, 10 thousands of years of development and we almost threw all that away in less than an hour, that the nukes of both sides in the cold war would've needed to fuck up the whole planet. That's the scary barrier.

The other barrier is space travel/sustainable technology, because if we don't get our shit together before we fuck up our environment (things like global warming), then we're super screwed. We'd be screwed too if something bad would happen to earth/our solar system, if we don't have a colony somewhere else.

Last but not least, we're the only species, that broke the technology barrier, that we know of. Even if there are million millions of earth like planets. We don't know the odds for breaking those barriers. There are so many things that could've gone wrong..maybe we just got lucky, because we are smart, social and have hands to build stuff..if we would've had flippers we'd be just sitting on the shore blowing bubbles..

If there are other species, that made it, then they're obviously way out of communications range. It's not like we have faster than light communication either. If the next smartest species is even just 100k light years away, then we wouldn't hear from them in ages and with a 100k ly latency, there would be no useful communication anyway..