Your declaration flies in the face of evidence in just this war. Ukraine has bombed multiple of their own bridges to slow Russian advances and/or to cut Russian supply lines.

Ukraine is currently shelling a Russian occupied nuclear power plant. If the plant blows, the nuclear fallout will most definitely affect Ukrainian citizens, but Ukraine sees the advantages as outweighing the negatives in such a scenario.

Currently Russia has a large number of pontoon bridges downstream from the Kherson dam. If Ukraine is planning an offensive, blowing the dam would flood the river downstream and wipe out all those Russian temporary bridges. This would cut off Russian troops from supplies and reinforcements for at least some days until the bridges could be rebuilt.

That would provide a huge advantage to the attacking Ukrainian forces. Of course Ukraine would risk civlian lives if it meant a crushing victory for them, potentially even taking back the city from Russia.