Yes, the current speculations in this field are of wildly varying quality. The argument about convergent evolution is sound.

Minor quibble about convergent evolution which doesn't change the conclusion much about there being other intelligent systems out there.

All organisms on Earth share some common points (though there might be shadow biospheres), like similar environmental conditions (a rocky planet with a moon, a certain span of temperatures, etc.), a certain biochemical basis (proteins, nucleic acids, water as a solvent, etc.). I'd distinguish convergent evolution within the same system of life on the one hand, and convergent evolution in different systems of life on the other. We have observed the first, and they both likely overlap, but some traits may not be as universal as we'd be lead to think.

For instance, eyes may be pretty useful here, but deep in the oceans of a world like Europa, provided life is possible there, they might not (an instance of the environment conditioning what is likely to evolve).