It is yes, but it's not that simple. 100% base, 30% from Soul weapon, elemental (dis)advantage and two Eidolons form the whole thing.
So you could be looking at Rudra users going against Thunder at 100%+30%-25%+100%+100% = 305%
And you compare that to Icarus Wind going with 100%+30%+45%+45%+100% = 320%
You have to remember that the Wind team will have a massively better Full Burst (since Full Burst Bonus double-dips into elemental (dis)advantage modifier), and that Wind team takes like half damage compared to Water, and Water has trouble debuffing. It usually boils down to "how good are your debuffs?" since if the Water team has -50%/-50% thanks to Miracle tickets, but the Wind team is -20%/-20% from Sniper Shot... then it doesn't really even matter which team you run. Wind would still probably be better because of the difference in Full Bursts.
Umm, point is, 100% are extremely powerful. But as said by others, they form only one part of the puzzle - a part that you can't really get outside of massive whaling (average cost of each 100% is about 4200 bucks I think? forgot, there's a thread about gacha chances) or rerolling. You CAN get really far with just a 100% Eidolon, though.