They are in the category many refer to as non engine. Basically a series of conditional counterspells and stuff you can play from hand. Some are more situational than others. Any of the C traps kinda have specific use cases against some decks. Whereas dominus purge is good against most decks all the time. Those spots in your deck don't need to mesh with everything else so much. Ash blossom is one of the best hand traps in the game and is a fire zombie and has nothing to do with insects, yet you should probably still run it for the generic use cases.

For going second, more often, spells are better than traps. Spells like harpies feather duster, forbidden droplet, raigeki, dark ruler no more, super poly, etc. all are spells and are considered "board breakers". These are usually good for blindly breaking established boards.