This type of capture rule, normally has two steps, and a player needs to choose to either capture the opponent’s piece, or forgo the opportunity and move a piece. So by willingly “sacrifice” a piece that is currently not doing anything (like a weak group), you can delay two of the opponent’s pieces. Most time, it’s not the best idea to waste movement “sente” to just capture one piece. A small local victory, doesn’t win the war, when the victory gains too little, and the investment is too high.
And the delay tactic is common across many strategy games, using a weak group to hold a stronger part of the opponent’s, and eliminate the weaker one.