Carbon is not just a little bit better than other elements at forming polymers and complex molecules it is many orders of magnitude better, and it's hugely abundant. Many complex carbon-based molecules are even formed in entirely non-biological processes in significant quantities. Ethanol, ribose, glycine, adenine, and others, for example. The overall nature of life in the Universe may prove to be quite a surprise to us humans but for now the overwhelming scientific consensus is that carbon based chemistry is by far the most likely route for life to develop anywhere.

there are lots of technical reasons that are perfectly valid, true, but it's not absolutely necessary.

It is safer to be a carbon chauvinist if you accept that ancient Mars was covered with oceans. A silicon-based microbe would be hard pressed to explain its distaste for water to its carbon-based neighbor.