Basic idea if there are less ults constantly in play, smaller plays like single picks and stuff can lead into bigger stuff since they are less restricted by ult economy. If support ults are less common, they can't afford to blow them and turn fights all the time. It means its less likely for a team to be able to do a full ult fight directly after a take. There's more wiggle room for people to build ult if they made one fuck up but recovered.
Its a huge deal that comes with a ton of net positives, because the ult economy as it functions right now is borderline broken, and it's not a new topic. The overall net positive is that variance in ult charges will be down in general.