i dont think many people are saying DB is bad. theres just alot of comparisons to SS which is weird because while they are similar, their uses were very different. if you used SS right (and im guessing theres a good amount of people who didnt) then SS was something you casted between fights as insurance and to delay damage in the upcoming fight, not really mid fight as some seem to have wanted to do. though it was useful to counter tank busters too.
But DB is only ment to be used in combat as a counter to an upcoming attack which is kinda the opposite of what SS was mostly used for.
Even though they are similar, they are used in different situations and they are both good spells just different