If platoons and mixing/matching have increased in recent years, there are two contributing factors:
Teams are better able to parse matchup data using meaningful inputs. Not "x batter is 3 for 5 against y pitcher," but "The swing path of x batter is compatible against the pitch shape of pitcher y." Also, L/L splits tend to be extreme. If you want the same lineup and order against LHP and RHP, that is ineffective.
Teams know better about the importance of rest, and may be able to use biomechanics/analytics to know when players need a day off to recharge or reduce injury risk.