A truly reliable decarbonized grid depends on dispatchable low carbon reserve capacity. Hydrogen offers one approach for providing that. It's not the only approach, however, and not automatically the best.
Other approaches include advanced nuclear capacity; large, low-cost flow batteries; advanced geology-independent pumped hydroelectric storage; advanced forms of compressed air energy storage; advanced forms of gravity energy storage; Stratosolar PV energy platforms; Allam cycle power plants; closed loop geothermal with boosted thermal storage; and the approach most favored by RE manufacturers and the RE advocacy community: massive overbuilding of RE capacity, supplemented by massive storage.
That's not an exhaustive list, and the various approaches aren't mutually exclusive. There are even some positive synergies from mixing them. But notice how many of them were labeled as "advanced". Lot of D&D work (development and demonstration) needed.