That's not entirely true. The study itself lists several previous works that only introduced the peanut allergen in varying amount over time. The results of tho

That's not entirely true. The study itself lists several previous works that only introduced the peanut allergen in varying amount over time. The results of those studies show that yes the body increasingly builds antibodies while the allergen is introduced but those effects diminish rapidly after the treatment is stopped. The importance of this work is that with the simultaneous introduction of this bacteria the effect is maintained for years. The bacteria plays a important role in allowing the body to retain the immunity. "Moreover, because there was no convincing evidence that allergen OITalone was effective in promoting sustained unresponsiveness at the time our randomized controlled trial (RCT) was designed and initiated, we elected to undertake a clinical trial evaluating whether coadministration of Lactobacillus rhamnosus CGMCC 1.3724 (NCC4007) and peanut OIT can induce sustained unresponsiveness to peanut among children with peanut allergy (Australian New Zealand Clinical Trials Registry ACTRN 12608000594325, 25/11/2008). This probiotic was selected based on its demonstrated tolerance-promoting effects, including induction of regulatory T and TH1 cytokine responses."